To ascertain the existence of an excess of avoidable mortality among psychiatric patients in an area with a community-based system of care, to identify predictors of higher risk of avoidable mortality and to provide some possible indication to reduce avoidable mortality in modern psychiatric services. All patients with an ICD-10 psychiatric diagnosis, living in a catchment area of about 75,000 inhabitants, seeking care in 1982-2001 were included (n = 6956). Mortality and causes of death were ascertained using linkage procedures with other local health databases. Standardized mortality ratios (SMRs) were calculated for each avoidable cause of death. The observed number of deaths for those causes considered avoidable by the European Community was four times greater than the expected (P < 0.01). SMR was higher for deaths preventable with adequate health promotion policies than for those preventable with appropriate health care. Males, alcohol/drug addicted and young patients have the highest avoidable SMRs. These findings urgently call for the implementation of health promotion and preventive programs targeted to psychiatric patients. Moreover, mental health services should improve the capacity to manage medical health problems of their patients.