An attempt was made in this study to develop a composite profile of personality characteristics of medical students that correlated differentially with successful achievement outcomes in the Psychiatry CLerkship at a University of Toronto teaching hospital. Data on 27 of 33 final year medical students in a psychiatry rotation programme were used to analyse canonical correlations between personality and achievement variables. The findings of the study indicated that success in clinical examinations was significantly correlated (R = 0.64, P less than 0.001) with a personality defined as apprehensive, anxious and less neurotic. Success on oral examinations was significantly correlated (R = 0.37, P less than 0.01) with a personality defined as anxious, more neurotic and extroverted. Success in objective multiple choice tests was not significantly correlated (R = 0.21, P = 0.10) with any particular personality profile, but the direction of the correlations suggested a personality describable as less intelligent (concrete thinking), apprehensive, adjusted and introverted. Although the small sample makes conclusions tentative, the findings are that students' personality differentially affect their examination results.