Free Practice Questions for USMLE Step 1

Exam-style questions and explanations by OpenExamPrep.

✓ No registration✓ No credit card

200+ Questions

100% Free

Loading practice questions...

Same family resources

Explore More USMLE

Continue into nearby exams from the same family. Each card keeps practice questions, study guides, flashcards, videos, and articles in one place.

More From This Family

Videos and articles for deeper review.

VideoUSMLE Step 1 Exam Guide 2026: FREE Pass/Fail Plan + May 14 FormatThis exam ArticleUSMLE Step 1 Exam Guide 2026: FREE Pass/Fail Plan + May 14 Format42 min read

Exam Review

Key Facts: USMLE Step 1 Exam

93%

U.S. MD First-Taker Pass Rate

USMLE 2025

280

Maximum Questions

USMLE Content Outline

Total Testing Time

USMLE

Question Blocks

USMLE

45-55%

Pathology Content

USMLE Content Description

$695

Exam Fee

2026 USMLE Fee Schedule

USMLE Step 1 transitioned to Pass/Fail scoring for exams administered on or after January 26, 2022. The exam has up to 280 multiple-choice items in an 8-hour testing session. Since May 14, 2026, it is divided into 14 thirty-minute blocks of up to 20 items each. The exam emphasizes integrated systems-based thinking and clinical vignettes requiring application of basic science knowledge to patient-care scenarios.

Sample USMLE Step 1 Practice Questions

Try these sample questions to review concepts for the USMLE Step 1 exam. Each question includes a detailed explanation. Start the interactive quiz above for the full 200+ question experience with AI tutoring.

1A 45-year-old man presents with fatigue and jaundice. Laboratory studies show elevated unconjugated bilirubin. Which enzyme deficiency is most likely responsible for this presentation?

A.Glucose-6-phosphate dehydrogenase

B.UDP-glucuronosyltransferase

C.Phenylalanine hydroxylase

D.Homogentisic acid oxidase

Explanation: UDP-glucuronosyltransferase is responsible for conjugating bilirubin in the liver. Deficiency (as in Gilbert syndrome or Crigler-Najjar syndrome) results in unconjugated hyperbilirubinemia. G6PD deficiency causes hemolytic anemia with indirect hyperbilirubinemia but is not an enzyme deficiency in the liver conjugation pathway.

2A 2-year-old child presents with developmental delay, intellectual disability, and a musty odor to the urine. Which dietary restriction is essential for this patient?

A.Galactose

B.Phenylalanine

C.Fructose

D.Leucine

Explanation: Phenylketonuria (PKU) is caused by phenylalanine hydroxylase deficiency, leading to accumulation of phenylalanine and its metabolites. The musty odor is from phenylacetic acid. Treatment requires lifelong restriction of phenylalanine intake.

3A researcher is studying a signaling pathway where a ligand binds to a receptor tyrosine kinase, leading to cell proliferation. Which of the following is the most likely downstream signaling molecule in this pathway?

A.cAMP

B.Ras protein

C.IP3

D.Nitric oxide

Explanation: Receptor tyrosine kinases (RTKs) typically signal through the Ras-MAPK pathway for cell proliferation. cAMP is associated with G-protein coupled receptors (Gs), IP3 with Gq-coupled receptors, and nitric oxide with soluble guanylate cyclase signaling.

4A 6-month-old infant presents with fasting hypoglycemia, hepatomegaly, and lactic acidosis. A liver biopsy shows glycogen accumulation. Which enzyme deficiency is most likely?

A.Glucose-6-phosphatase

B.Glycogen phosphorylase

C.Branching enzyme

D.Debranching enzyme

Explanation: Glucose-6-phosphatase deficiency (von Gierke disease or Type I glycogen storage disease) presents with severe fasting hypoglycemia, lactic acidosis, hyperuricemia, and hepatomegaly due to glycogen and fat accumulation in the liver.

5A patient with a history of alcohol abuse presents with neurological symptoms including ophthalmoplegia, ataxia, and confusion. Which vitamin deficiency is most likely responsible?

A.Vitamin B12

B.Thiamine (Vitamin B1)

C.Folate

D.Niacin

Explanation: The triad of ophthalmoplegia (CN III, IV, VI palsies), ataxia, and confusion is classic for Wernicke encephalopathy caused by thiamine deficiency, commonly seen in alcoholics. Untreated, this can progress to Korsakoff psychosis.

6A newborn presents with lethargy, vomiting, and jaundice shortly after introducing breast milk. Laboratory studies show elevated galactose and galactitol in the blood. Which enzyme is deficient?

A.Galactokinase

B.Galactose-1-phosphate uridyltransferase

C.Lactase

D.Aldolase B

Explanation: Classic galactosemia is caused by galactose-1-phosphate uridyltransferase deficiency. Symptoms appear with lactose/galactose ingestion and include vomiting, jaundice, hepatomegaly, cataracts, and intellectual disability if untreated.

7A patient with chronic granulomatous disease develops recurrent infections with catalase-positive organisms. What is the underlying defect in this condition?

A.Defective neutrophil chemotaxis

B.Defective NADPH oxidase complex

C.Defective CD18 integrin

D.Defective myeloperoxidase

Explanation: Chronic granulomatous disease (CGD) is caused by defects in the NADPH oxidase complex, preventing the respiratory burst and superoxide generation needed to kill catalase-positive organisms like Staphylococcus aureus, Burkholderia cepacia, and Aspergillus.

8A cell line is found to have a mutation in the p53 gene. Which cellular process is most likely impaired?

A.DNA repair and cell cycle checkpoint control

B.Protein synthesis initiation

C.Lipid metabolism

D.Glycolysis regulation

Explanation: p53 is the "guardian of the genome" that regulates cell cycle checkpoints (G1/S arrest), DNA repair, and apoptosis in response to DNA damage. Loss of p53 function is the most common genetic alteration in human cancers.

9A patient presents with muscle weakness and myoglobinuria after vigorous exercise. Which metabolic pathway is most likely impaired?

A.Gluconeogenesis

B.Glycogenolysis

C.Fatty acid oxidation

D.Ketogenesis

Explanation: Fatty acid oxidation defects (e.g., carnitine palmitoyltransferase II deficiency) are the most common cause of recurrent rhabdomyolysis and myoglobinuria triggered by prolonged or vigorous exercise, fasting, or illness, because muscle cannot use fatty acids for energy once glycogen is depleted. They also present with non-ketotic hypoglycemia and cardiomyopathy. McArdle disease (glycogenolysis defect) classically causes a 'second wind' phenomenon with early-exercise cramps rather than rhabdomyolysis from sustained exertion.

10Which enzyme catalyzes the rate-limiting step in cholesterol synthesis?

A.HMG-CoA synthase

B.HMG-CoA reductase

C.HMG-CoA lyase

D.Acetyl-CoA carboxylase

Explanation: HMG-CoA reductase catalyzes the conversion of HMG-CoA to mevalonate, the rate-limiting step in cholesterol synthesis. It is the target of statin drugs. HMG-CoA lyase is involved in ketogenesis, and acetyl-CoA carboxylase is the rate-limiting enzyme in fatty acid synthesis.

About the USMLE Step 1 Exam

USMLE Step 1 assesses foundational understanding of health, disease, and therapeutic principles across organ systems. Current official system ranges include Reproductive & Endocrine Systems (12-16%), Respiratory & Renal/Urinary Systems (11-15%), Behavioral Health & Nervous Systems/Special Senses (10-14%), Blood & Lymphoreticular/Immune Systems (9-13%), Multisystem Processes & Disorders (8-12%), Musculoskeletal/Skin/Subcutaneous Tissue (8-12%), Cardiovascular System (7-11%), Gastrointestinal System (6-10%), Social Sciences/Communication (6-9%), Biostatistics/Epidemiology/Population Health (4-6%), and Human Development (1-3%). Discipline coverage is mechanism-heavy, with pathology (45-55%) and physiology (30-40%) carrying the largest ranges.

Exam sponsor: FSMB and NBME. The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Questions

280 questions

Time Limit

8 hours; 14 x 30-minute blocks (since May 14, 2026)

Passing Score

Pass/Fail (since January 2022)

Exam / Certification Fees

$695

Exam sponsor website

Reported exam pass rate: 93%. 2025 first-taker pass rate for U.S. MD students; U.S. DO first-taker pass rate was 89% and the first-taker pass rate for examinees from non-U.S. schools (including Canadian schools from 2025) was 75% This describes exam candidates, not OpenExamPrep users or results from using our resources. Exam sponsor website

Fees, eligibility, and exam policies can change. Confirm them with the exam sponsor before applying or paying.

Official sources

Our practice resources: topics covered

We aim to reflect publicly available exam outlines and topic information in our study resources. Coverage, format, and difficulty may differ from the actual exam, and we cannot guarantee that every detail is accurate or current. Confirm exam requirements, fees, and policies with the official exam sponsor.

1-3%

Human Development

Normal age-related findings and care of the well patient topics

9-13%

Blood & Lymphoreticular/Immune Systems

Hematologic, lymphatic, and immune-related foundational and disease content

10-14%

Behavioral Health & Nervous Systems/Special Senses

Behavioral science plus neurologic and sensory system content

8-12%

Musculoskeletal, Skin & Subcutaneous Tissue

Musculoskeletal and integumentary structure, pathology, and care principles

7-11%

Cardiovascular System

Cardiovascular mechanisms, pathology, and therapeutic concepts

11-15%

Respiratory & Renal/Urinary Systems

Pulmonary and renal/urinary integrated system coverage

6-10%

Gastrointestinal System

GI physiology, pathology, and related management principles

12-16%

Reproductive & Endocrine Systems

Reproductive and endocrine foundational and disease content

8-12%

Multisystem Processes & Disorders

Cross-system pathophysiology and broad disease-process integration

4-6%

Biostatistics & Epidemiology/Population Health

Statistics, epidemiology, and population-health interpretation skills

6-9%

Social Sciences: Communication and Interpersonal Skills

Communication and social science content relevant to clinical practice

Preparing for the USMLE Step 1 Exam

What You Need to Know

Passing score: Pass/Fail (since January 2022)
Exam length: 280 questions
Time limit: 8 hours; 14 x 30-minute blocks (since May 14, 2026)
Exam / certification fees: $695 Official sources

Using Our Practice Resources

Work through all 200 available questions
Review every answer and explanation
Track weak areas and revisit them
Use our AI tutor for tough concepts

USMLE Step 1: Suggested Study Strategy

1Master pathology mechanisms - understand the 'why' behind disease processes, not just facts

2Practice clinical vignettes extensively - Step 1 emphasizes application of basic science to patient scenarios

3Use spaced repetition for memorization-heavy topics like microbiology, pharmacology, and biochemistry

4Weight study time by the official system ranges: Reproductive & Endocrine (12-16%), Respiratory & Renal/Urinary (11-15%) and Behavioral Health & Nervous Systems/Special Senses (10-14%) are the largest

5Review biostatistics thoroughly - these concepts are often under-studied but consistently tested

Frequently Asked Questions

What is the USMLE Step 1 pass rate?

In 2025 USMLE performance data, Step 1 first-taker pass rates were 93% for U.S. MD examinees, 89% for U.S. DO examinees, and 75% for examinees from non-U.S. schools (Canadian schools are grouped with non-U.S. schools from 2025). Pass/fail scoring began for exams administered on or after January 26, 2022.

How is USMLE Step 1 scored?

Since January 26, 2022, Step 1 outcomes are reported as Pass/Fail only. USMLE notes that the passing standard corresponds to 196 on the prior three-digit scale, but future Step 1 passing-standard reviews will not be reported as three-digit scores.

How many questions are on USMLE Step 1?

Step 1 contains up to 280 multiple-choice items in one 8-hour testing session. Since May 14, 2026, it is divided into 14 thirty-minute blocks of up to 20 items each.

How long should I study for Step 1?

Most students dedicate 4-8 weeks of dedicated study time, with 6-8 hours of focused study daily. Total preparation typically spans 6-12 months of ongoing review during preclinical years plus dedicated study period.

What is the best way to prepare for Step 1?

USMLE states that broad-based learning in the basic sciences is the best preparation, and examinees should use the official content outline, sample test materials, and self-assessment resources. Focus on mechanisms and clinical applications rather than rote memorization.

Can I retake Step 1 if I fail?

Yes. You may not take the same Step more than three times within a 12-month period, and a fourth attempt must be at least 12 months after your first attempt and at least six months after your most recent attempt. After four attempts without passing, you are ineligible to apply for any Step.