Mortality rates and cause of death are reported from a long-term follow-up study of 620 Swedish criminals who were subjects of a forensic psychiatric examination in 1965-1968. The results show that there is an increased mortality rate in criminals mainly due to violent deaths (suicides, accidents) and diseases related to alcohol abuse. The increased mortality was found in all age groups throughout the follow-up period of 13-16 years. The total mortality was 17%. An analysis of different mortality risk factors showed that drug abuse, type of crime (violent crimes or property crimes) and criminal recidivism did not further increase the mortality risk. There were relatively few deaths due to overdose of drugs. Alcohol abuse increased the mortality rate significantly.