If you’re a medical student, you’ve probably heard of the CBSE, or Comprehensive Basic Science Examination. Some also refer to this simply as the “comp” exam. It’s a standardized exam offered by the National Board of Medical Examiners that approximates the content on the USMLE Step 1 exam.
A lot of students wonder what’s on the CBSE and how to prepare for it. If you’re one of them, we can help! This article covers everything you need to know about the exam and how to study for it so you achieve your highest possible score. We’ll start with a bit of information on why you need to take the CBSE and what your score can tell you.
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What is the NBME CBSE?
CBSE exams are administered through your medical school and are designed to assess your knowledge from the preclinical years of medical training. The score you get on the CBSE is translated into a Step 1 equivalent score, which should help you get a sense of where you stand with your Step 1 preparation.
The CBSE will help you identify strengths and weaknesses across basic science subjects and it serves as a benchmark for your performance relative to national standards.
Which subjects are tested on the NBME CBSE?
The CBSE is a general, integrated achievement test covering material typically learned during basic science education, with somewhat more emphasis on second-year courses in medical schools. The exam reflects content coverage on USMLE Step 1 and uses the same item formats and even some old USMLE Step 1 questions.
The CBSE has two basic parts (or axis): foundational science systems and physician tasks/competencies.
For each axis, here’s the percentage of questions that are dedicated to a particular topic:
Foundational Science Systems
- Human Development (1%–3%)
- Blood & Lymphoreticular/Immune Systems (9%–13%)
- Behavioral Health & Nervous Systems/Special Senses (10%–14%)
- Musculoskeletal, Skin & Subcutaneous Tissue (8%–12%)
- Cardiovascular System (7%–11%)
- Respiratory & Renal/Urinary Systems (11%–15%)
- Gastrointestinal System (6%–10%)
- Reproductive & Endocrine Systems (12%–16%)
- Multisystem Processes & Disorders (8%–12%)
- Biostatistics & Epidemiology/Population Health (4%–6%)
- Social Sciences: Communication and Interpersonal Skills (6%–9%)
Physician Tasks/Competencies Specifications
- Medical Knowledge: Applying Foundational Science Concepts (60%–70%)
- Patient Care: Diagnosis (20%–25%)
- Communication and Interpersonal Skills (6%–9%)
- Practice-Based Learning & Improvement (4%–6%)
For updated content and topics the exam covers, visit the NBME website.
When do I take the NBME CBSE?
When you take the NBME CBSE really depends on how your medical school uses the exam. In my medical school, we took the CBSE at the end of our preclinical years just before our dedicated Step 1 examination time. This seems to be fairly standard at most medical schools.
For us, the CBSE score was revealed only to the examinee and it wasn’t used as any type of evaluation. Instead, the goal was to give us an indication of where we stood as we designed our study schedule. Other schools require you to pass the CBSE before sitting for your dedicated Step 1 study period and before you start clinical rotations.
How does the CBSE compare to the actual Step 1 exam?
Again, the format is meant to mimic USMLE Step 1 and although the exact format can change over time, the CBSE generally consists of multiple-choice questions with a single best answer. The exam is administered on a computer with testing software and interfaces similar to those used on the USMLE.
The NBME CBSE exam is:
- 200 multiple-choice questions
- 4 blocks (with 50 questions each)
- About 5 hours long (You have 75 minutes to complete each block.)
Compare this to Step 1, which is (after May 14, 2026):
- 280 multiple-choice questions
- 14 blocks
- About 8 hours (Each block is 30 minutes and you get breaks.)
- 20 questions per block (The number of questions per block on a given examination form may vary, but it doesn’t exceed 20.)
To sum up, the CBSE is written by the same folks who design Step 1, so the two exams are pretty similar. In fact, many of the questions on the CBSE are actually taken from prior Step 1 Qbanks.
However, while the CBSE isn’t as long as Step 1 overall, the blocks are actually a bit longer than those you’ll encounter on the USMLE. Additionally, the CBSE tends to have more “first-order” questions with short vignettes than your Step 1 prep material, but in general it’s fairly similar to the real Step 1 exam, which is why it is such a good gauge.
What study materials should I use for the NBME CBSE?
Remember that the NBME CBSE is designed to mimic USMLE Step 1. So prepare for it like you would prepare for Step 1! This is a great opportunity to try out different study resources and whittle them down to those that are most useful.
Think of the CBSE as a low-stakes way to evaluate your knowledge and the success of your study strategies to date. Then, come day one of your dedicated period, you’ll be able to hit the ground running.
For those who need to pass the NBME CBSE prior to their dedicated study period (and are not using it as simply a formative testing experience), the best resource is the Comprehensive Basic Science Self-Assessment (CBSSA).
The CBSSA is the self-administered equivalent of the CBSE. There are multiple CBSSAs available for purchase, so you can take one to start and then more as you progress through your weeks of preparation to see the improvement. Each version of the exam is $62 and can be purchased through the official NBME website.
After finishing each self-assessment, you’ll be given a score report that shares valuable insight into your testing habits and where your strengths and weaknesses are. I highly recommend the CBSSA for the CBSE and USMLE.
Each CBSSA is:
- 200 multiple-choice questions
- 4 question blocks
- About 5 hours (Each block is 1 hour, 15 minutes.)
Remember, this is meant to prepare you for the big leagues, which is USMLE. So you should study accordingly. Be sure to check our Med Study Planner, which can help you set up a study schedule. Try it now for free!
How should I study for the NBME CBSE?
Keep in mind that you’ll be trying to study for the CBSE while still learning new things in your classes. It’s extremely important to keep your coursework as the main priority! Focus on doing as well as you can on it, as it’ll only help you during your dedicated Step 1 study period.
That being said, try to make time each day(even if it’s only 20-30 minutes)to do the following:
1. Review Qbank questions as much as possible.
With each question in your Step 1 Qbank, make sure to read the answer explanation thoroughly. Then, supplement your learning with the corresponding pages in First Aid. Now is not the time to read First Aid cover to cover! Instead, just read short excerpts that apply to the question you’re answering.
2. Watch Sketchy videos (Micro, Pharm, +/- Path).
Make sure to keep using this resource if you find it helpful.
3. Select Pathoma chapters/videos.
Again, if this resource has been helpful, keep using it!
4. Take two or three CBSSA exams.
Be sure to review the tests carefully afterwards, as most of your learning will come from your review. Also, be sure not to take them all, as it’s important to save some for your dedicated Step 1 study period.
What should I expect on exam day?
On test day, you can expect a testing experience similar to what you’ll experience for Step 1, though your medical school may have its own procedures for check-in and scheduling compared to a Prometric testing site.
To make sure things go as smoothly as possible, here are a few tips on what to do from start to finish:
Before the Exam
- Arrive early (typically 5-15 minutes before your scheduled start time).
- Bring the identification required by your school and check in, get seated in your assigned seat, and log into the exam software.
- Don’t worry about exam instructions beforehand (The testing software and rules will be explained before you begin.)
During the Exam
- You’ll encounter multiple-choice questions that require a single best answer.
- There will be a countdown timer for each block.
- Mark questions to review later within the current block.
- Change answers before the block ends.
- You can’t return to a block once you submit it or time expires.
Breaks
- Depending on your school’s administration, there may be scheduled breaks between blocks.
- Some schools allow flexible break time, while others have fixed breaks.
- Use breaks to hydrate, eat a light snack, and use the bathroom when permitted.
When will I receive my NBME CBSE score report?
You should receive an electronic score from NBME within one to two weeks of taking the exam. The CBSSA score reports are generated shortly after completion of the test.
What do I do with my NBME CBSE exam results?
Like with any NBME score report, use the information to create an effective study plan for the real Step 1. Take a look at your performance profile on the score report and identify your weakest areas. Plan to set aside about two or three hours each day during your dedicated Step 1 study period to focus on them, even if the rest of your day is spent looking at other systems or subjects. It’s important to work in daily review of these tough topics.
Once you take your first NBME practice test during your dedicated Step 1 study period, compare the score report’s performance profile to your practice results to see if you made any improvements in these troublesome areas. If there are still some areas that are particularly challenging, plan to sprinkle in several days of extra study time to focus on those topics.
The key is to learn and grow from your exam results rather than feel embarrassed or disappointed. This is a learning opportunity that will only make you a stronger test taker on the real exam!
Final Thoughts
We hope this guide gives you a better sense of what the NBME CBSE is and how to prepare for it. Prep hard for the exam, as it can give you a good indication of what areas you need to focus on for Step 1. Good luck with your preparation, and be sure to reach out if you have any questions.
And for more Step 1 tips, check out these other posts on the blog:
