A Guttman stages of drug use model was confirmed for Australian youth in this systematic household survey of 13-17-year-olds in Perth (n = 1093). The same model held for both sexes and all ages although the model was more efficient for the older youth. General drug use prevalence, expansion of drug repertoire and frequency of use all increased with age. Multiple drug use was prevalent. Marijuana use was not a necessary stage for the progression to other illicit drug use as 29% of current users of other illicit drugs reported never using marijuana. The hazard rate for use of marijuana or other illicit drugs, if one was a current tobacco smoker, was high. Alcohol and tobacco were implicated as important 'gateway' drugs though hazard rates showed tobacco to be the more important of the two. Implications of the study are that delaying or eliminating the onset of tobacco use are important goals of prevention programmes and that multiple drug use should be recognized and addressed in health education programmes for youth.