Social Medicine, Kronan Health Centre, S-17283 Sundby-

The role of family background as well as behavioural and psychological factors as risk factors for intravenous drug abuse was analysed in a longitudinal study of 8168 Swedish men conscripted for military service in 1969-70. Informa-tion about risk factors was obtained from a survey of all Swedish conscripts. Records on intravenous drug abuse, during a followup ending in 1986, were obtained from a survey of intravenous drug abusers among persons brought to the Central police arrest in Stockholm. Strong predictors of intravenous drug abuse were contact with the police or juvenile authorities (RR = 22.3 95 % CI 15.1-33.0), high alcohol consumption (RR = 9.2 95 % CI 6.7-12.7) and psychiatric diagnosis at conscription (RR = 6.0 95 % CI 4.5-8.1) and low social class (RR = 3,695 % CI 2.2-5.9). In multivariate analyses, these factors and indicators of de