A double-blind trial of a smoking-withdrawal chewing gum containing 2 mg nicotine was conducted with 100 consecutive patients in a smoking cessation clinic. All patients received the usual psychological treatment given at the clinic. In addition, the patients were randomly assigned to a nicotine gum (the experimental group) or a placebo chewing gum (control group). The abstinence rates for the experimental group at 1, 3, and 6 months after quitting were 90, 76, and 63%, respectively. The comparable abstinence rates for the control group were 60, 52, and 45%. The differences were significant at the 5% level at all three follow-up periods. When nicotine dependence, as measured by a standard questionnaire, was taken into consideration, it was found that 71% of the high-nicotine-dependent smokers in the experimental group were abstinent after 6 months, as compared to 39% in the placebo group. In contrast, low-nicotine-dependent patients achieved 75 and 65%, respectively, for the same time interval. The gum was well accepted by patients and gave no serious side effects.