Objective: To investigate associations between the percentage and severity of mental disorders (MD) and three different primary health care (PHC) strategies in Brazil: traditional care (TC), the Family Health Strategy (FHS), and FHS with shared mental health care (FHS+SC). Methods: Random samples were selected from three different areas of a Brazilian city. Each area was served by a different PHC strategy (TC, FHS, or FHS+SC). Five mental health professionals, blinded to the type of PHC strategy delivered in each area, conducted interviews using the Mini International Neuropsychiatric Interview (MINI) and other specific instruments to assess the prevalence and severity of MD. Results: 530 subjects were interviewed. The TC strategy was significantly associated with a higher percentage of MD when compared to FHS and FHS+SC. These results were not affected by adjustment for sociodemographic variables. The difference in prevalence of MD between the two FHS areas (with and without SC) was not statistically significant. No significant differences in MD severity were observed across the three PHC strategies. Conclusion: Areas covered by FHS showed a lower percentage of MD than those covered by TC. Presence of SC did not influence the prevalence of MD, suggesting that mental-health training of FHS teams may have minimized the influence of SC.