To investigate adolescent drug use behaviour, a random community sample of Sydney teenagers aged 14 to 19 years was interviewed at home in 1985 (N=996) and again in 1986 (N=756). Respondents were asked about current use of alcohol, tobacco, marijuana, other illicit drugs, medications and inhalants. Drug use was common: 16 per cent of respondents were heavy drinkers, 28 per cent smoked tobacco, 10 per cent used marijuana and 4 per cent used drugs other than alcohol, tobacco or marijuana. Seventeen per cent were multiple drug users. Drug use was more common among boys than girls, except for tobacco smoking, and increased with age: older males had particularly high prevalences of heavy drinking, tobacco and marijuana use. The prevalence of heavy drinking, tobacco and marijuana use increased by 2–3 percent over the one year follow‐up period. About half of the heavy drinkers and marijuana users, and 80 per cent of tobacco smokers had not changed one year later, which indicates the stability of these behaviours. One‐third of eligible teenagers contacted at the first interview declined to participate: it is likely that this study underestimates the prevalence of drug use in the community. Heavy drinking, tobacco smoking and marijuana use remain important target behaviours for adolescent drug use prevention programs.