The present study aimed to determine mortality rates and trends among community mental health service users in Bologna (Italy) between 2001 and 2013. Standardized mortality ratios (SMRs) were calculated, and Poisson multiple regression analysis was performed. The cohort comprised 42,357 patients, of which 3556 died. The overall SMR was 1.62 (95% confidence interval = 1.57-1.67). SMRs for natural causes of death ranged from 1.25 to 2.30, whereas the SMR for violent deaths was 3.45. Both serious and common mental disorders showed a significant excess of mortality, although higher rates were found in severe mental disorders, especially in personality disorders. Different from most published studies, the overall SMR slightly decreased during the study period. The present study, though confirming that people with mental disorders present a higher risk of mortality, calls for prevention strategies oriented to all psychiatric diagnoses.