Overview
The International Biology Olympiad (IBO) is described by its organisers as the premier worldwide biology competition for high school students. The winners of national biology olympiads from more than 70 countries and regions take part each year. A student cannot register directly. The details below follow the IBO Operational Guidelines, version 7.0 (5 September 2026).
Who can take part
Winners of the national biology olympiad (NBO) in the current school year in the country they represent.
Students of a regular secondary school for general education in that country.
Born on or after 1 July of the competition year minus twenty.
Students who have taken part in the IBO fewer than two times before.
Students without a diploma that allows university study.
Students not trained or instructed within a selected group of 50 or fewer, including the IBO team, for longer than two weeks.
A standard delegation has at most four students and two jury members.
Exam pattern
The competition has a theoretical and a practical (experimental) examination. The guidelines recommend four to six hours for each part, with a break, and at least one day between the two. The practical tasks test laboratory skills, and the theoretical tasks test understanding and processing of biological knowledge, with set proportions per topic. The host decides the number of tasks and the practical topics.
Marking and results
The final score gives theory and practical equal weight, using a t-score method, and is rescaled to 50 plus 10 times the final t-score. Medals are decided by a mathematical procedure without jury discussion, with cutoffs based on 10 percent of competitors for gold, 30 percent for gold or silver and 60 percent for any medal, each placed at the largest score gap near that rank. Up to 70 percent of competitors, plus two, may receive an award including the certificate of merit. Results are announced for individual students, not national teams. The IBO website also lists a Tomas Soukup Award.
How to take part
Take part in your country's national biology olympiad rounds. Only the national winner or winners are sent to the international event. Each national organiser handles registration, selection and travel.
Preparation tips
Practise laboratory skills, since the practical exam carries half of the score.
Past IBO exams are published online two years after each competition.
The IBO has no official syllabus, so study biology beyond the school curriculum.
Note
Dates, host country and detailed rules change every year. Confirm them on the official IBO website or with your national olympiad office.