Nicotine replacement therapy (NRT) is an effective smoking cessation treatment, but little information is available about how primary care physicians use the therapy. We investigated the quality of UK general practitioners' (GPs') advice against smoking, including how frequently they recommend NRT to smokers. We compared the characteristics of smokers whom GPs recommended use NRT with smokers who did not receive GP recommendations. We conducted a cross-sectional survey of 3,525 adult patients attending 35 UK GPs over a 16-month period. Of those surveyed, 2,955 eligible patients (83.8%) completed preconsultation questionnaires, and 1,026 (34.7%) were regular smokers, with 927 (90.4%) of the regular smokers completing postconsultation questionnaires. Of those completing the questionnaires, 20.2% (95% CI, 17.7% to 22.9%) or 187 recalled discussion of smoking with their GPs and of these, 66.3% (95% CI, 60.1% to 74.1%) or 124 perceived that they had been given an unequivocal message to stop smoking. Although 60.4% of smokers (606 of 1,004) (95% CI, 57.3% to 63.3%) or smoked more than 10 cigarettes daily, only 17.6% (95% CI, 12.9% to 23.7%) or 33 of those recalling antismoking advice reported discussion of NRT. Accordingly, GPs discussed NRT with only a minority of smokers who might benefit from the therapy. Intending to give up smoking in the next 4 weeks was the only variable independently associated with smokers' recall of discussing NRT (OR=2.58 [95% CI 1.20% to 5.57%]). The study findings thus provide only limited information to support the notion that UK GPs recommend NRT in an evidence-based manner. Now that NRT is available by prescription from UK GPs, further research is needed to monitor whether this effective antismoking therapy is being prescribed appropriately.