We examined the pharmacokinetics of a transdermal nicotine patch and evaluated the usefulness of such a patch in a pilot smoking-cessation program. Use of the patch was associated with plasma nicotine concentrations that were comparable to smoking or to the use of other smoking-cessation devices. However, these plasma concentrations were maintained for 24 hours, and the patch appeared to be suitable for use once a day. Its use in a 6-week placebo-controlled double-blind study resulted in a significant degree of smoking cessation or in reduction of smoking activity. The findings suggest that it may be valuable to extend investigations to a larger population and that transdermal nicotine may have a useful role in smoking-cessation therapy.