Background: Multiple variables affect medical specialty choice, including temperament, sociodemographic factors, and personal experiences. Many studies address specific variables for specific specialties, but few assess the relative impact of each factor. Purpose: To identify the relative influence of temperament in choosing a specialty. Methods: A sociodemographic and personal experiences questionnaire and a 240-question temperament and character inventory was distributed to 682 medical students. Their scores for 6 medical specialties were examined using analyses of variance, multivariate analyses of variance, and discriminant analysis. Results: Students choosing surgery, emergency medicine, and obstetrics and gynecology were higher on novelty seeking than other students. Future surgeons were lower in harm avoidance and reward dependence (RD) than the others. Students choosing primary care specialties, emergency medicine, and obstetrics and gynecology were all high on RD; with pediatrics being highest. Students differed from college students, the women differed from the men, and the Asian Americans differed from the other groups. Conclusion: The implications of these findings are discussed for career counseling and future research.