Nine hundred eight-three new intercollegiate athletes were evaluated to estimate the frequency of exercise-induced asthma (EIA). Medical history was obtained using a specifically structured interview. Athletes were selected for exercise testing based on positive responses to questions regarding symptoms of respiratory distress after strenuous exercise. Exercise testing was performed in a controlled laboratory setting using a standard exercise protocol. A laboratory diagnosis of EIA was made if the forced expiratory volume in one second (FEV1) fell greater than or equal to 10%, forced expiratory flow at 25% to 75% of vital capacity (FEF25-75%) fell greater than or equal to 20%, and/or peak expiratory flow rate (PEFR) fell greater than or equal to 12.5% after exercise. The frequency of EIA was 2.8%; only nine of the 28 athletes with EIA were detected prior to arrival at college.