The study found that main causes of death were drug-related; 18 deaths were specifically due to drug overdose, and most deaths were among people being prescribed opiates at the time. The mean mortality rate was 1.84 percent annually, and the excess mortality ratio was 11.9. This excess was highest at the beginning and varied over the study period, appearing to be higher when the clinics opened and again in the mid-1980's. No sex differences in mortality rates were demonstrated, but excess mortality was concentrated in younger age groups. No prediction of the 85 survivors could be made on the basis of length of heroin use prior to the study. Although the use of official records limited data accuracy, it seemed that almost all deaths were either a direct or an indirect consequence of drug use and that most of those who died were using drugs just prior to their death. 25 references, 5 tables, and 1 figure