How the USA Biology Olympiad works
USABO is a four-stage national competition run by the Center for Excellence in Education. Students in China enter through the Open Exam (BIOUS) and earn China-region awards using the same papers and judging standard.
From one exam to the world stage
The full USABO pathway runs in four stages. In China, students enter through the Open Exam (BIOUS) and earn China-region awards; the Semifinal and National Finals are the United States team-selection path. About the China region →
Open Exam
50 multiple-choice questions in 50 minutes, open to Grades 9–12. In the United States the exam is taken online; in China (BIOUS) it is 50 questions, paper-based at your school. This is the entry point for China-region students.
Semifinal Exam
The top 10% of Open Exam scorers who are US citizens or legal residents — approximately 600 students — are invited to a longer, harder paper. The Semifinal is the first US-citizenship-gated stage.
National Finals
The top 20 students from the Semifinal are invited to a host university for a 12-day residential programme: 10 days of intensive instruction followed by 2 days of testing, including laboratory practicals.
International Biology Olympiad
A four-student national team is selected to represent the USA at the IBO. In 2026, the 37th IBO is held in Vilnius, Lithuania (Vilnius University), July 12–19.
Who can enter
Open Exam
High-school students in Grades 9–12. In China, students sit the exam through a partnering school as part of the BIOUS programme. No citizenship requirement at this stage.
Semifinal & beyond
From the Semifinal onward, advancement requires US citizenship or legal residency. These stages form the US national team-selection pathway and are not available to China-region students.
China-region path
Students in China sit the Open Exam at a partnering school and earn China-region (BIOUS) awards by percentile. See registration for school eligibility and deadlines.
Awards at every level
In the United States, Open Exam recognitions include an Honorable Mention for the top 20% of scorers and a Certificate of Merit for the top 30%. The Semifinal carries additional awards for the top 50 and next 175 qualifiers.
In the China region (BIOUS), awards are assigned by national percentile: Top Gold (top 5%), Gold (top 15%), Silver (top 30%), Bronze (top 45%), and a Regional Honorable for the regional top 25%.
China-region awards →
What the exam tests
The USABO Open Exam covers seven topic areas drawn from the IBO syllabus. Questions reward understanding and application, not recall alone.
For preparation advice and recommended texts, see resources →
Other biology olympiads
British Biology Olympiad (BBO)
The British Biology Olympiad is another well-known biology olympiad that many students also consider alongside USABO. Both competitions test biology at the pre-university level.
Compare in the newsroom →Questions about the competition?
Talk to a USABO advisor about the exam, eligibility or the China-region pathway.