While there is ample documentation that medical training is stressful, less is known about predictive variables that might identify students who have the most difficulty in managing stress during medical training. Depression and anxiety in first year medical students were investigated in a longitudinal design. One-hundred and twenty-one medical students (81% of the class) were surveyed. The first survey took place immediately prior to the beginning of medical training (wave 1); the second survey was approximately 8 months after the beginning of classes (wave 2). Medical students who began their first year with relatively low 'A' level grades, high ratings of state anxiety and depression, high trait anxiety and low dispositional optimism, and reliance on avoidant coping strategies were found to be at higher risk for developing depression and anxiety symptoms at wave 2. Students reported increased concern about curriculum and environment, personal competence and endurance, and time to have a life outside medical school at wave 2, compared to their reports at wave 1. Increase in concerns correlated with an increase in depression and anxiety. At both surveys, use of avoidant coping strategies resulted in increased depression and anxiety; at wave 2, active coping and positive reinterpretation resulted in decreased depression and anxiety. These findings suggest characteristics of vulnerable students who might be identified early in their first year and provided with additional support. Educating students to expect an increase in concerns about environment and personal ability to manage the academic load might make these concerns less overwhelming. In addition, information about effective coping strategies (i.e. active coping efforts) and ineffective means of dealing with stress (avoidant coping efforts) might be helpful in preventing distress.