A survey of first-year medical students at the University of Toronto shows that academic factors are viewed as the most stressful and social factors as the least stressful. Among anticipated sources of stress those dealing with perceived failure are highly stressful, and those dealing with sexual aspects of the doctor-patient relationship are much less so. Factor analysis reveals that sources of stress are multidimensional rather than unidimensional. Particular socio-demographic antecedent variables are much more highly correlated with stress than are others. In particular, it is found that students in subgroups differing from "mainstream" students feel more stress than their mainstream counterparts. Feelings of stress are also found to be positively related to possible consequences of stress, such as frequency of thinking about dropping out and to number of days off school because of illness.