To determine whether physicians with harm avoidance (HA) personality traits were more prone to developing increased anxiety and depression during the medical internship.A prospective longitudinal study of 74 medical interns was carried out using repeated measures of symptoms of anxiety and depression with the Beck Anxiety and Depression Inventories (BAI and BDI) before, at the 3rd, 6th, and 12th months during the internship, and 2 weeks after the internship was completed. Baseline personality was assessed by the Tridimensional Personality Questionnaire with 3 dimensions: novelty-seeking, HA, and reward dependence (RD).Levels of both depression and anxiety increased (6.4 and 3.4 on scores for BDI and BAI, respectively) during the internship and returned to baseline 2 weeks after it ended. HA scores were significantly correlated with depression and anxiety (0.3 scores on both the BDI and the BAI) and the scores for RD were significantly correlated with anxiety but not with depression. The interaction of HA and point in internship showed no significant differences.Internship plays a major role in the increase in depression and anxiety. A HA personality was also associated with the development of both depression and anxiety.