Underwent or Undergone? Depends on the tense and sentence structure. Undergo is the base verb, underwent is the simple past, and undergone is the past participle. Use underwent for a completed past action: “She underwent surgery last year.” Use undergone after an auxiliary verb such as has, have, or had: “She has undergone treatment.”
This difference matters in medical reports, academic writing, business emails, and everyday communication. For example, “The company underwent major changes” describes a completed event, while “The company has undergone major changes” connects the past experience with the present.
A simple guide makes the choice easier: undergo for the base form, underwent for the past, and undergone for perfect tense constructions. Understanding this grammar rule improves clarity, prevents confusion, and helps you use these verbs accurately in real writing and speaking.
Undergo, Underwent, and Undergone: The Basic Idea
The verb undergo describes experiencing something, passing through a process, or enduring an event. Consequently, it commonly appears with medical procedures, major changes, training, testing, renovations, and other significant experiences.
Here are the main forms:
| Verb form | Word | Example |
|---|---|---|
| Base form | undergo | Patients may undergo testing. |
| Third-person singular | undergoes | She undergoes treatment regularly. |
| Present participle | undergoing | She is undergoing treatment. |
| Simple past | underwent | She underwent treatment yesterday. |
| Past participle | undergone | She has undergone treatment. |
The easiest pattern to remember is:
undergo → underwent → undergone
Interestingly, this pattern resembles another familiar irregular verb:
go → went → gone
That similarity can help you remember why “has underwent” is incorrect. After all, you wouldn’t normally say “has went.” Instead, you say “has gone.” Likewise, you say “has undergone.”
Quick rule: Use underwent for the simple past, and use undergone after a perfect-tense helping verb such as has, have, or had.
What Does “Undergo” Mean?
Undergo means to experience, endure, or pass through something. Generally, the word describes an experience that involves a noticeable process, change, challenge, or procedure.
For instance:
- The patient will undergo surgery tomorrow.
- All applicants must undergo a background check.
- The company plans to undergo major restructuring.
- Students may undergo additional training.
- The building will undergo extensive repairs.
Furthermore, the verb is transitive, which means it normally takes a direct object. In other words, you undergo something.
For example:
- undergo surgery
- undergo treatment
- undergo testing
- undergo training
- undergo a transformation
- undergo changes
- undergo an examination
Because of this, you wouldn’t usually say simply, “She underwent.” Rather, the listener expects to know what she experienced or went through.
Common meanings of “undergo”
Depending on context, undergo can mean:
- Experience something — The company underwent rapid growth.
- Endure something — The community underwent severe hardship.
- Receive a procedure or treatment — He underwent surgery.
- Pass through a process of change — The industry is undergoing major changes.
Overall, Merriam-Webster gives endure and go through/experience as central meanings of the verb.
What Does “Underwent” Mean?
Underwent is the simple past tense of undergo. Therefore, you use it when describing an event that happened in the past.
Importantly, underwent can function as the main verb by itself.
Examples
- She underwent surgery last month.
- The company underwent a major transformation in 2024.
- He underwent extensive training before starting the job.
- The building underwent renovation after the storm.
- The patient underwent several tests.
Notice the sentence structure:
Subject + underwent + object
For example:
The patient + underwent + surgery.
In this construction, you don’t need has, have, or had before underwent, since you’re using the simple past.
When should you choose “underwent”?
Look for a completed event in the past, especially when the sentence identifies when it happened.
Common time expressions include:
- yesterday
- last week
- last year
- in 2020
- two months ago
- during the summer
- before the meeting
For example:
She underwent surgery last year.
Here, the phrase last year places the action at a completed point in the past, so underwent fits naturally.
What Does “Undergone” Mean?
Undergone is the past participle of undergo. Unlike the simple past underwent, however, it normally appears as part of a larger verb construction.
Most commonly, you’ll see it after:
- has
- have
- had
Examples:
- She has undergone surgery.
- They have undergone extensive training.
- The company has undergone major changes.
- He had undergone several tests before the operation.
The difference becomes obvious once you compare the structures:
- Simple past: She underwent surgery.
- Present perfect: She has undergone surgery.
- Past perfect: She had undergone surgery.
Notably, the event itself may be similar; what changes is the grammatical relationship to time.
In fact, Cambridge specifically identifies undergone as the past participle of undergo and provides examples such as “He seems to have undergone a change in attitude recently.”
Underwent vs. Undergone: The Key Difference
The most important distinction is simple:
| Underwent | Undergone |
|---|---|
| Simple past | Past participle |
| Can stand as the main verb | Usually works with an auxiliary verb |
| Describes a completed past event | Commonly appears in perfect constructions |
| Often used with a finished past time | Often connects a past experience with another time or the present |
| She underwent surgery yesterday. | She has undergone surgery. |
To put it simply, think of the two forms as different tools.
Underwent tells you that something happened, whereas undergone helps build a verb phrase that places that experience in relation to another point in time.
Compare these sentences
She underwent surgery in May. This sentence gives us a completed past event; the time is specific.
She has undergone surgery. By contrast, this sentence focuses on the experience and its relevance to the present, rather than simply locating it at a finished past time.
Ultimately, neither sentence is automatically “more correct.” Rather, the surrounding grammar determines which form belongs there.
Underwent vs. Undergone in Different Sentence Structures
Simple Past With “Underwent”
Use underwent when the sentence describes a completed action in the past. For example:
- The athlete underwent surgery in June.
- The factory underwent repairs after the accident.
- She underwent training before joining the team.
- The organization underwent significant changes last year.
Typically, a specific past-time expression makes the choice obvious.
Incorrect: She undergone surgery yesterday. Correct: She underwent surgery yesterday.
Present Perfect With “Undergone”
The present perfect follows this pattern:
has/have + past participle
Therefore:
has/have + undergone
Examples:
- She has undergone surgery.
- They have undergone extensive testing.
- The company has undergone restructuring.
- The system has undergone several upgrades.
Notably, the present perfect often matters when the past experience has some connection to the present. For instance:
The building has undergone several renovations.
Here, the sentence doesn’t merely report a finished event; instead, it highlights the building’s history of changes and their relevance to its current state.
Past Perfect With “Undergone”
The past perfect follows:
had + past participle
So the correct structure is:
had undergone
For example:
Before joining the company, Maria had undergone extensive professional training.
Here, the training happened before another event in the past: joining the company.
Similarly, by the time the doctor examined him, he had undergone several tests. In this case, the testing happened first, and the examination came later — which is exactly what the past perfect helps communicate.
Modal and Other Constructions
The verb undergo also appears after modal verbs and other structures. For example:
- Patients must undergo testing.
- The building will undergo repairs.
- Applicants may undergo an interview.
- The system can undergo further changes.
Notice that these sentences don’t use underwent or undergone. Instead, after modal verbs such as will, may, must, can, and should, use the base form:
modal + undergo
Thus:
Correct: The machine will undergo testing. Incorrect: The machine will underwent testing.
Underwent vs. Undergone Examples in Real-World Contexts
The distinction becomes much easier once you see it in situations where the verb naturally appears.
Medical and Health Contexts
Medical writing frequently uses undergo, since patients experience procedures, examinations, treatments, and operations.
- Simple past: The patient underwent surgery on Monday.
- Present perfect: The patient has undergone three surgeries.
- Past perfect: The patient had undergone several tests before receiving the diagnosis.
- Future: The patient will undergo additional testing next week.
Taken together, these examples demonstrate that the choice depends on the verb construction, not on the medical meaning.
Education and Training
Likewise, the verb works naturally with learning and professional development:
- The new employees underwent training last month.
- All candidates must undergo orientation.
- The teachers have undergone additional training.
- She had undergone specialized training before applying.
As you can see, the same grammatical rule remains intact even though the context changes.
Business and Organizational Change
Similarly, companies, buildings, systems, and industries can also undergo change. For example:
The company underwent a major restructuring in 2023.
Or, put in present perfect terms:
The company has undergone significant changes since 2023.
Here, the first sentence presents a completed past event, while the second emphasizes a period of change that has relevance to the present. Current dictionary examples also show undergo being used for renovations, reorganizations, testing, and other forms of change.
Personal and Social Experiences
You can also use undergo for significant personal experiences, such as:
- He underwent a difficult period after losing his job.
- She has undergone a remarkable transformation.
- They had undergone many challenges before reaching success.
That said, the word can sound more formal than everyday alternatives such as experience or go through. For casual conversation, you might say:
“She went through a difficult time.”
Whereas in formal writing, you might see:
“She underwent a difficult period of adjustment.”
Both communicate a similar idea, though their tone differs.
Common Mistakes With “Underwent” and “Undergone”
“I Have Underwent Surgery”
This is one of the most common mistakes.
Incorrect: I have underwent surgery. Correct: I have undergone surgery.
Why? Because have requires the past participle in the present perfect. The pattern is have + undergone, not have + underwent.
“She Undergone Surgery Yesterday”
This sentence mistakenly uses the past participle where the simple past is required.
Incorrect: She undergone surgery yesterday. Correct: She underwent surgery yesterday.
Since the word yesterday points to a completed past event, and no auxiliary verb is present, underwent is the correct form.
“He Had Underwent Training”
The past perfect requires had + past participle.
Incorrect: He had underwent training. Correct: He had undergone training.
Remember: had undergone follows the same grammatical pattern as had gone, had written, had seen, and had taken.
“She Has Underwent Several Changes”
Again, has requires the past participle.
Incorrect: She has underwent several changes. Correct: She has undergone several changes.
As a useful mental check, try substituting another irregular verb for undergo. You wouldn’t say:
She has went through many changes.
Instead, you’d say:
She has gone through many changes.
Therefore:
She has undergone many changes.
How to Remember Underwent vs. Undergone
Fortunately, a small memory trick can save you from a surprisingly common grammar mistake.
Remember the “go” pattern
First, think: go → went → gone
Then connect it with: undergo → underwent → undergone
While the endings aren’t identical in every detail, the pattern is closely related and useful for remembering the forms.
Use the time test
Ask yourself:
Did it happen at a completed time in the past?
If yes, underwent will often be the right choice:
She underwent surgery last year.
Next, ask:
Does the sentence contain has, have, or had?
If so, you will normally need undergone:
She has undergone surgery.
Together, this two-question check works remarkably well.
Undergo Verb Forms at a Glance
| Form | Usage | Example |
|---|---|---|
| undergo | Base form | They will undergo testing. |
| undergoes | Present tense, third person | The system undergoes regular checks. |
| undergoing | Present participle | The system is undergoing repairs. |
| underwent | Simple past | The system underwent repairs yesterday. |
| undergone | Past participle | The system has undergone repairs. |
One detail deserves particular attention: undergone isn’t simply another way to say “underwent.” Rather, it has a different grammatical job — and that distinction is the heart of the entire issue.
Underwent vs. Undergone: A Quick Test
Choose the correct form in each sentence.
- She ___ surgery last year.
- She has ___ surgery.
- The company ___ major changes in 2024.
- The company has ___ major changes.
- He had ___ extensive training before applying.
- The patient will ___ additional tests.
Answers
- underwent
- undergone
- underwent
- undergone
- undergone
- undergo
As you can see, the pattern is consistent:
- Past event: underwent
- Has/have/had: undergone
- Modal or future construction: undergo
Underwent vs. Undergone in Formal and Everyday English
To be clear, neither underwent nor undergone is inherently more formal than the other; the difference comes from grammar, not formality.
That said, undergo itself often appears in formal, professional, medical, academic, and technical writing. Cambridge notes its use for experiences, changes, and medical procedures, while dictionary examples show it across medical, business, scientific, and organizational contexts.
In casual conversation, however, speakers often choose simpler alternatives.
More formal: The organization underwent substantial restructuring. More conversational: The organization went through major changes.
Both are grammatical; the first simply sounds more polished and institutional, while the second feels more conversational.
Related Irregular Verb Forms You Should Know
Naturally, undergo belongs to the world of irregular English verbs, so its forms don’t follow the regular -ed pattern.
You don’t say:
❌ undergoed
Instead, you say:
- underwent for the simple past
- undergone for the past participle
A useful comparison is:
| Base | Simple past | Past participle |
|---|---|---|
| go | went | gone |
| undergo | underwent | undergone |
| begin | began | begun |
| take | took | taken |
| write | wrote | written |
For this reason, memorizing the complete three-part form is more useful than memorizing only underwent.
Undergo → underwent → undergone. Learn the trio as one unit.
Underwent or Undergone? Quick Answer
If you’re still unsure, use this rule:
Use “underwent” as the simple past form. Use “undergone” as the past participle.
- Use underwent: She underwent surgery last week.
- Use undergone: She has undergone surgery.
- Use undergo: She will undergo surgery next week.
In short, the tense determines the form.
| Situation | Correct form | Example |
|---|---|---|
| Present/base | undergo | They will undergo testing. |
| Simple past | underwent | They underwent testing yesterday. |
| Present perfect | undergone | They have undergone testing. |
| Past perfect | undergone | They had undergone testing. |
| Present continuous | undergoing | They are undergoing testing. |
Frequently Asked Questions
Q1: What is the difference between underwent and undergone?
Underwent is the simple past form of undergo, while undergone is the past participle. For example, “She underwent surgery yesterday” uses the simple past, whereas “She has undergone surgery” uses the past participle.
Q2: Can “underwent” and “undergone” be used interchangeably?
No. Although they can describe the same general experience, they serve different grammatical functions: underwent works as a simple past verb, while undergone normally appears with an auxiliary verb.
Q3: Is “I have underwent” correct?
No. The correct sentence is: I have undergone surgery. After have, use the past participle undergone.
Q4: Should I say “underwent surgery” or “undergone surgery”?
Both can be correct, depending on the sentence: She underwent surgery yesterday (simple past) versus She has undergone surgery (present perfect).
Q5: Why do we say “has undergone” instead of “has underwent”?
Because has + past participle forms the present perfect, and the past participle of undergo is undergone.
Q6: Is “undergone” the past tense of undergo? No. The simple past is underwent; undergone is the past participle.
Q7: Can “undergone” be used without has, have, or had?
It can appear in other grammatical constructions, but in ordinary active perfect-tense sentences, it commonly follows has, have, or had. For learners, the safest pattern to remember is has/have/had + undergone.
Q8: Is “underwent” correct in spoken English?
Yes, underwent is completely standard English. That said, everyday speakers may sometimes choose went through or experienced instead, since those alternatives sound more conversational.
Q9: What is the easiest way to remember underwent and undergone?
Simply remember: Yesterday → underwent, and Has/have/had → undergone. For example: Yesterday, she underwent treatment versus She has undergone treatment. That simple contrast covers most everyday situations.
Conclusion
Choosing between underwent and undergone becomes much easier when you focus on their grammatical roles. Underwent is the simple past form, as in, “She underwent surgery last year.” Undergone, however, is the past participle, so it usually follows has, have, or had: “She has undergone surgery.”
Remember the pattern: undergo → underwent → undergone. Use underwent for a completed past event and undergone in perfect-tense structures. Once this distinction becomes familiar, common mistakes such as “has underwent” and “she undergone yesterday” become easy to spot and correct.