To prospectively assess effects of doses of a nicotine-replacement agent on weight gain in men and women after smoking cessation. Four-week, randomized, double-blind clinical trial. Outpatient medical clinic. Healthy volunteers who smoked at least 10 cigarettes per day. Pharmacologic: Random assignment to 0, 2, or 4 mg of nicotine polacrilex on a fixed-dose schedule (one piece per hour while awake). Behavioral: Brief, medical/behavioral counseling regarding smoking cessation. Weight change as a function of dose and gender only in participants abstinent for all 4 week. (Self-reported abstinence verified by breath carbon monoxide levels). Weight change in women abstinent for 4 weeks (n = 16) was +1.69, +0.33, and -0.26 kg in the placebo, 2-mg, and 4-mg groups, respectively, compared with +1.60, +1.45, and +1.18 kg for the men who were abstinent for 4 weeks (n = 19). Medication use did not differ as a function of dose or gender. Nicotine polacrilex suppressed, in a dose-related fashion, weight gain after smoking cessation in successfully treated women. Weight gain was not shown to be suppressed in men, possibly because of small sample size.