OBJECTIVE: Research in the USA has demonstrated numerous associations between adult attention-deficit/hyperactivity disorder (ADHD) and smoking behaviour; however, no specific work on this topic has been done in Switzerland. The aim of the study was to gain knowledge about the association between ADHD and tobacco consumption in a Swiss sample of adult ADHD patients. METHODS: The study subjects were recruited from patients with a DSM-IV diagnosis of ADHD consecutively presenting to the ADHD consultation service at the Centre for Addiction Disorders, an outpatient facility of the Zurich University Hospital, between September 2000 and January 2006. Complete data could be obtained from 100 of 134 patients presenting to the service. RESULTS: The number of current smokers in the ADHD sample was significantly elevated compared to the Swiss general population (55 vs 31%). Additionally, daily smokers in the ADHD sample smoked significantly more cigarettes per day, reported higher levels of nicotine dependence and started to smoke regularly at a significantly younger age. The motivation to quit smoking was high. CONCLUSIONS: The results of this Swiss study are consistent with previous research in the USA. The fact that many adults with ADHD are motivated to quit smoking and that they actually make use of support in quitting is crucial for secondary tobacco prevention.