We used data from different sources to estimate the extent and the trend of the epidemic of drug use in Italy in the second half of the '80s. During the study period, the number of subjects attending drug dependency units increased from 13,905 to 61,689. Mortality and morbidity indicators showed an increase in both drug related deaths (mainly from overdose) and AIDS cases reported in injecting drug users, particularly among older subjects. However, the number of young adults detected as drug users at the army recruitment remained virtually stable from 1986 on. These findings suggest that both demand and availability of treatment increased through the years 1985-89, and that clinical consequences of drug use related behaviour have become an important public health priority.