BACKGROUND A large share of premature mortality is Spain in related with the abuse of addictive substances: tobacco, alcohol and non-institutionalized drugs. Adolescence is a key period for the adoption of their use. An accurate knowledge of the attitudes, beliefs, environmental perceptions and behaviours of teen-agers is necessary for the design and evaluation of preventive interventions. METHODS Data were obtained from a survey conducted in 1992 on smoking, alcohol and non-institutionalized drugs in 8th grade students (13-14 years old) of a representative sample of the schools of the city of Barcelona (Catalonia, Spain). RESULTS Up to 44.1% have ever smoked, 10.9% are regular smokers and 15.5% have bought tobacco at some point. There are no differences in smoking patterns by sex at this age. Even if 35.5% never drink alcohol, 1.7% drink it daily, 15.5% drink on week-ends and 62.9% at family celebrations, while 13.5% have bought alcohol at some point and 22.4% report having got drunk at least once. There are no differences by sex in alcohol use at this age. Concerning non-institutionalized drugs, 35.4% of the students think that many adults use them, and 22.4% say that some friends have tried them. CONCLUSIONS The results show the increasing penetration of tobacco and alcohol in the personal environment of the students, and the process of initiation. Compared with previous studies in this population, we can estimate a modest and non-significant reduction of regular smoking, and a reduction in daily and regular alcohol use.