BACKGROUND: Studies have shown that adolescents with attention-deficit/hyperactivity disorder (ADHD) have an increased risk of alcohol and substance abuse in adulthood. An unequivocal reason for this association has not yet been identified but it has been shown that pharmacological treatment is likely to reduce this risk. AIMS: To test whether adolescents with ADHD in pharmacological treatment have a higher prevalence of smoking and use of alcohol and drugs than a matched control group from the general population. The study will also analyse associations between smoking, alcohol and drug use and comorbid psychiatric symptoms. METHODS: The sample in this case-control study comprised 219 adolescents aged 13-18 years, including a case group of 117 adolescents with ADHD and a control group of 102 adolescents without ADHD. Participating subjects completed a questionnaire about their use of cigarettes, drugs and alcohol and the self-report version of the Strengths and Difficulties Questionnaire (SDQ). RESULTS: 21% of ADHD probands vs. 16% controls were daily smokers (P = 0.326). Among alcohol users, 52% of ADHD probands vs. 70% controls confirmed monthly alcohol intake (P = 0.014); 4% of cases compared with 7% of controls used illicit drugs within last month (P = 0.260). CONCLUSION: No significant group differences were found in the prevalence of ever having smoked cigarettes, drinking alcohol or using illicit drugs between adolescents with ADHD and controls. Contrary to expectations, subjects in the control group had a more regular and heavier use of alcohol. However, ADHD patients had a heavier use of cigarettes than controls.