OBJECTIVE This study examined longitudinal patterns of narcotics use, other substance use, criminal involvement, morbidity, and mortality among narcotics addicts. METHODS A 24-year follow-up study. Data were obtained from admission records and two face-to-face interviews conducted in 1974-1975 and 1985-1986. METHODS Five hundred eighty-one narcotics addicts admitted to the California Civil Addict Program during the years 1962 through 1964. RESULTS Most of this sample initiated narcotics use before age 20 years and had a mean age at program admission of 25.4 years. In 1974-1975, 13.8% of the sample died and 28.6% tested negative for opiates. Corresponding rates in 1985-1986 were 27.7% and 25.0%, respectively. Substance use and criminal involvement remained high among this sample into their late 40s. In any given year during the 10 years prior to the 1985-1986 interview, less than 10% of the sample participated in community-based treatment programs such as methadone maintenance. Disability, long periods of heavy alcohol use, heavy criminal involvement, and tobacco use were among the strongest correlates of mortality. CONCLUSIONS The results suggest that the eventual cessation of narcotics use is a very slow process, unlikely to occur for some addicts, especially if they have not ceased use by their late 30s.