SUMMARY OBJECTIVE To study depression symptoms' incidence of medical interns (first year of medical residency) and its correlation with occupational characteristics, satisfaction and stress about their training program. METHODS Prospective Cohort Study conducted at Escola Paulista de Medicina, Universidade Federal de São Paulo. First year residents, N = 166, from a teaching hospital were invited to answer the Beck Depression Inventory (BDI) and an occupational questionnaire in a prospective longitudinal study. BDI score variation was related with socio-demographic aspects and occupational characteristics using linear regression models. RESULTS 111 subjects participated (67%); the BDI-score increased in 8 months (mean = 2.75 ± 3.29 vs. 7.00 ± 5.66; p<0.0001). The depressive symptoms' incidence was 9.01% (score>15). BDI-score variation had mean = 4.25 ± 4.93, ranging from -8 to 28. Residents not satisfied with professional training acquired (β = 3.44; p = 0.004), with their personal life (β = 2.97; p = 0.001), or who felt stressed in the relationship with senior residents (β = 2.91; p = 0.015) presented 3 more points of BDI-score after 8 months comparing to those without these perceptions; and being unsatisfied with the nursing team increased BDI-score after 8 months in 2 more points (β = 1.95; p = 0.025). CONCLUSION Among the factors that interfere with depression in interns is the occupational characteristics, which might be enhanced by the training facility. Addressing these dissatisfaction and stressful issues should help the university provide better care of interns' mental health.