USABO, administered by the Center for Excellence in Education, is the premier high school biology competition in the United States and the official selection route to the International Biology Olympiad. It runs in four stages: Open Exam, Semifinal Exam, National Finals, IBO.
The Open Exam is a 50-minute online multiple-choice test taken simultaneously nationwide by all registered grade 9-12 students, spanning cell and molecular biology, genetics and evolution, plant and animal anatomy and physiology, ecology, animal behaviour and systematics — far beyond a standard school syllabus. Because the clock is tight, speed and judgment matter as much as breadth.
Roughly the top 10% advance to the Semifinal, where difficulty jumps sharply: 120 minutes across three parts, adding multiple true/false items that punish imprecise concepts and short-answer or essay questions tied to the current IBO themes. From this round, only U.S. citizens and permanent residents may compete.
The top 50 qualify for the National Finals; after a Zoom interview and pretest, 20 National Finalists attend a roughly 12-day residential program at a host university — 10 days of university-level instruction and lab training, then a practical examination of about 6 hours and a theoretical examination of about 4 hours.
For 2026-27: registration opens 7 August 2026, school payment closes 23 October, registration closes 22 November, the Open Exam is 3 February 2027, the Semifinal 2 March, finalists announced 30 March, National Finals 20-30 June, and the IBO in Warsaw 18-25 July 2027.






