What Is on USMLE Step 1? Topics, Weightage and Exam Format (2026)
Written by Dr Zartasha Ali, MBBS, FCPS (Medicine). Reviewed by Dr Ammar Hussain, MBBS, FCPS (Pediatrics), MRCPCH.
USMLE Step 1 tests the basic sciences of medicine across 11 system categories and 11 disciplines, in up to 280 questions split into fourteen 30-minute blocks. Pathology is the largest discipline at 45 to 55 per cent. Reproductive and endocrine systems form the largest system category at 12 to 16 per cent.
Every figure on this page comes from usmle.org. We opened the pages on 14 October 2026 and list them at the end. The USMLE notes on its tables that “percentages are subject to change at any time”, so check the official page before your exam.
Which outline these figures are from
The tables below copy the Step 1 Content Outline and Specifications page as it stood on usmle.org on 14 October 2026. The page does not print an effective date or a version year. It is the outline in force for exams taken in 2026.
The exam format changed during 2026. The format in this guide applies to Step 1 exams taken on or after 14 May 2026.
USMLE Step 1 exam format: how many questions and blocks
According to the Step 1 Exam Content page on usmle.org, Step 1 is a one-day exam. “It is divided into fourteen 30-minute blocks and administered in one 8-hour testing session.”
| Item | Step 1 on or after 14 May 2026 | Step 1 before 14 May 2026 |
|---|---|---|
| Number of blocks | 14 | 7 |
| Length of each block | 30 minutes | 60 minutes |
| Questions per block | Up to 20 | Up to 40 |
| Total questions | Up to 280 | Up to 280 |
| Testing session | 8 hours | 8 hours |
| Minimum break time | 55 minutes | 45 minutes |
| Optional tutorial | 5 minutes | 15 minutes |
The USMLE’s notice of 14 May 2026 says that “the exam content, total number of items, and overall length of the tests remain unchanged.” Only the block structure and the software changed. The Exam Resources page gives the total as “up to 280 items” for both formats.
Thirty minutes for up to 20 questions works out at 90 seconds per question on a full block. The number of questions in a block can vary, so the time per question may be a little longer on some blocks.
You can review and change answers only inside the block you are working on. When a block ends, you cannot return to it.
How many questions are on Step 1
Step 1 has up to 280 questions. The official wording is “up to”, because the number of questions in a block “may vary, but does not exceed 20”. Fourteen blocks of 20 gives the maximum of 280.
What the questions look like
The Step 1 question formats page on usmle.org describes one format: single best answer. “A single patient-centered vignette is associated with one question followed by four or more response options.” The page calls this “the traditional, most frequently used multiple-choice question format on the examination.”
Some questions ask you to interpret a picture, graph or table. The page says “a portion of the questions involves interpretation of graphic or pictorial materials.”
There is no negative marking. The page advises: “If unsure about an answer, it is better to guess since unanswered questions are automatically counted as wrong answers.”
USMLE Step 1 topics by system (Table 1)
The first official table divides the exam by body system. This is the USMLE Step 1 blueprint that most students mean when they ask about weightage.
| System | Range, % |
|---|---|
| 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 |
Source: USMLE Step 1 Content Outline and Specifications, Table 1.
Three official notes belong with this table.
- Foundational science has no row of its own. The footnote says: “Foundational Science content is distributed throughout the organ systems based on disease process/diagnosis.” Biochemistry, genetics and cell biology are tested inside the systems.
- Human Development is narrow. The footnote says the topic “includes Normal Age-Related Findings and Care of the Well Patient.” Content from the old General Principles category has been moved into the organ systems.
- Several rows are pairs. Respiratory is grouped with renal, and reproductive with endocrine. The range covers both systems together.
USMLE Step 1 weightage by discipline (Table 3)
The third official table divides the same exam by subject. This table answers the question “which subjects are on Step 1”.
| Discipline | Range, % |
|---|---|
| Pathology | 45-55 |
| Physiology | 30-40 |
| Nutrition | 15-20 |
| Gross Anatomy & Embryology | 10-20 |
| Microbiology | 10-20 |
| Pharmacology | 10-20 |
| Behavioral Sciences | 10-15 |
| Biochemistry | 5-15 |
| Histology & Cell Biology | 5-15 |
| Immunology | 5-15 |
| Genetics | 5-10 |
Source: USMLE Step 1 Content Outline and Specifications, Table 3.
The page notes that these “totals add up to greater than 100%”. One question can count toward more than one discipline. A question about a drug that treats heart failure can count as pharmacology, physiology and pathology at once.
For this reason, do not read the table as a share of your study hours. Read it as a ranking. Pathology and physiology together sit behind most questions on the exam.
Physician tasks and competencies (Table 2)
The second official table describes what each question asks you to do with your knowledge.
| Competency | Range, % |
|---|---|
| Medical Knowledge: Applying Foundational Science Concepts | 60-70 |
| Patient Care: Diagnosis (History/Physical Examination; Diagnosis) | 20-25 |
| Communication and Interpersonal Skills | 6-9 |
| Practice-based Learning & Improvement | 4-6 |
Source: USMLE Step 1 Content Outline and Specifications, Table 2.
The table shows why Step 1 questions are written as patient cases. Between 60 and 70 per cent ask you to apply a science concept, often a mechanism. Another 20 to 25 per cent ask you to reach a diagnosis from the history, the examination or test results.
Practice-based learning and improvement is where biostatistics and study interpretation sit. Communication and interpersonal skills covers the questions about what to say to a patient.
How to read the USMLE Step 1 content outline
The three tables describe the same 280 questions from three directions. Each question has a system, one or more disciplines, and a task.
Take a question about a 60-year-old man with crushing chest pain and a blocked coronary artery. Its system is cardiovascular.
Its disciplines are pathology and perhaps gross anatomy. Its task is applying foundational science concepts.
The USMLE describes the purpose of the exam in one sentence: “Step 1 assesses whether you understand and can apply important concepts of the sciences basic to the practice of medicine.”
USMLE Step 1 syllabus: a subject checklist
The USMLE does not publish a syllabus in the school sense. The content outline is the nearest thing.
The checklist below combines the two official tables into one study list. The grouping is ours; the categories are the official ones.
| Study area | Official system rows it covers | Main disciplines |
|---|---|---|
| Blood and immune system | Blood & Lymphoreticular/Immune Systems | Pathology, immunology, pharmacology |
| Nervous system and psychiatry | Behavioral Health & Nervous Systems/Special Senses | Gross anatomy, pathology, pharmacology, behavioral sciences |
| Muscles, bones and skin | Musculoskeletal, Skin & Subcutaneous Tissue | Gross anatomy, pathology, histology |
| Heart and vessels | Cardiovascular System | Physiology, pathology, pharmacology |
| Lungs and kidneys | Respiratory & Renal/Urinary Systems | Physiology, pathology |
| Digestive system | Gastrointestinal System | Pathology, physiology, nutrition, microbiology |
| Reproductive and endocrine | Reproductive & Endocrine Systems | Physiology, pathology, embryology |
| Multisystem | Multisystem Processes & Disorders | Microbiology, nutrition, genetics, biochemistry |
| Statistics and public health | Biostatistics & Epidemiology/Population Health | Behavioral sciences |
| Communication and ethics | Social Sciences: Communication and Interpersonal Skills | Behavioral sciences |
| Growth and ageing | Human Development | Physiology |
For a list of topics inside each system, see our USMLE Step 1 high-yield topics guide.
How to use the weightage when you plan
Three practical rules follow from the tables.
- Do not skip the small rows. Biostatistics and communication together are 10 to 15 per cent of the exam. They take less time to learn than an organ system.
- Study by system, test by mixed block. The official outline is organised by system, so system-based study matches it. The exam mixes all systems in every block, so your later practice should be mixed as well.
- Give pathology and physiology the most time. Every organ system should be studied as normal function first, then disease.
Our USMLE Step 1 study schedule turns these rules into 3-month and 6-month plans.
Practice papers mapped to the outline
Each RecallsGuru paper is written by our authors and labelled with the system and discipline it covers, using the category names in the tables above. You can find them on the USMLE Step 1 recalls page. Each product has free sample questions.
Questions people ask
How many questions are on USMLE Step 1?
Up to 280. The usmle.org Exam Resources page lists Step 1 as “14 x 30-minute blocks | 8-hour testing session | Up to 280 items” for exams from 14 May 2026.
How many blocks are in Step 1?
Fourteen blocks of 30 minutes each, for exams on or after 14 May 2026. Before that date the exam had seven 60-minute blocks.
How long is the Step 1 exam?
One 8-hour testing session. This includes the testing blocks, a minimum of 55 minutes of break time and a 5-minute optional tutorial.
Which subject has the highest weightage on Step 1?
Pathology, at 45 to 55 per cent in the official discipline table. Physiology is second at 30 to 40 per cent.
Which system has the highest weightage?
Reproductive and endocrine systems together, at 12 to 16 per cent. Respiratory and renal/urinary systems together are next at 11 to 15 per cent.
Is anatomy on Step 1?
Yes. Gross anatomy and embryology are listed at 10 to 20 per cent. Histology and cell biology are listed separately at 5 to 15 per cent.
Is Step 1 scored or pass/fail?
Pass/fail. The USMLE common questions page says Step 1 exams taken since 26 January 2022 appear on transcripts “as a pass/fail outcome only, without a numeric score”.
Where can I see official sample questions?
On usmle.org. The Step 1 sample test questions page offers more than 100 sample questions as a PDF and as an interactive test in the new software.
Sources
All pages were opened on 14 October 2026.
- USMLE Step 1 Content Outline and Specifications: https://www.usmle.org/exam-resources/step-1-materials/step-1-content-outline-and-specifications
- USMLE Step 1 Exam Content: https://www.usmle.org/step-exams/step-1/step-1-exam-content
- USMLE Exam Resources: https://www.usmle.org/exam-resources
- USMLE Step 1 Formats and Questions: https://www.usmle.org/exam-resources/step-1-materials/step-1-test-question-formats
- USMLE Step 1 Sample Test Questions: https://www.usmle.org/exam-resources/step-1-materials/step-1-sample-test-questions
- Test Delivery Software Updates in Place for Step 1, 14 May 2026: https://www.usmle.org/test-delivery-software-updates-place-step-1
- USMLE Common Questions (Step 1): https://www.usmle.org/common-questions?query=Step+1