Knowledge of the timing of, reasons for, and frequency of major medical-career changes of medical school graduates is useful in considering physician manpower needs. This study reports aspects of the medical-career changes made by a cohort of Alberta medical school graduates who graduated from 1973-1985. Of the 603 (81%) who participated, 160 (27%) reported major medical career changes. Significantly more specialists (35%) than family physicians (18%) made major changes. Forty-two percent made changes during the first year of residency, 21% later in residency, and 29% after entering practice. Reasons cited included general dissatisfaction (47%), lifestyle compatibility (24%), and training and practice experiences (19%). This study indicates that while personal needs and preferences influence changes during residency, practice experience is also important to career choices.