To assess the feasibility of using primary care dentists and the dental team providing smoking cessation advice in practice. A prospective study to examine the success of a smoking cessation programme. 54 primary care dental practices in the UK. Training and educational materials were supplied to members of the dental team and to potential recruits smoking 10 or more cigarettes a day. Recruitment was over 6 months and subjects were followed up for 9 months. In addition to dentists' counselling, nicotine patches were made available, on request, at cost price. Salivary cotinine assay was used for validation of smoking levels at initial counselling and 9 months after recruitment. 54 practices were enrolled but only 22 recruited patients. Records of 154 eligible patients were evaluated. Compliance to attend follow up clinics was poor--only 74 reported at 9 months. Among them 17 (11%) were successful in giving-up tobacco for 9 months as validated by patient histories and salivary cotinine assay. A large variation performance of the dental practices was noted. Motivated dentists with staff support and access to information on smoking counselling are able to contribute to tobacco control measures in the community. The success of this programme closely parallels those reported in general medical practice settings. In view of the very considerable attrition rates found at all levels of the programme in the present study and the uneven performance of the participating practices the quit rate reported here may not accurately reflect what could be achieved in an individual primary care setting.