This study examines the relationship between personality, knowledge and teachers' evaluations of paediatric residents at a large, urban teaching hospital. All residents (n = 30) were graduates of foreign medical schools. Each resident completed the Myers-Briggs Type Indicator (MBTI) as a measure of personality and was rated (on a scale of 1-7) by teachers on each of 35 items representing 14 different aspects of clinical performance. These data were correlated with performance on the American Board of Pediatrics In-training Examination (ABPITE), and with demographic data. Ratings of knowledge were directly associated with scores on the ABPITE (r = 0.51, P < 0.01) and with the MBTI continuous score for extraversion (r = 0.51, P < 0.01), but inversely associated with age (r = -0.41, P < 0.01). ABPITE scores were also associated directly with MBTI Extraversion (r = 0.44, P < 0.01) and inversely with age (r = -0.56, P < 0.001). Age and MBTI Extraversion were independently significant predictors of ABPITE (Multiple R = 0.64, P < 0.01) and ratings of knowledge (Multiple R = 0.59, P < 0.01). Results suggest that teachers' evaluations of knowledge have validity, and that age and introversion/extroversion play a significant role in both subjective and objective evaluations of paediatric knowledge. Demographic and personality variables may be predictive of knowledge acquisition, but are unrelated to many dimensions of clinical performance.