In a placebo-controlled, double-blind, 2-year prospective study, 182 smokers were given either nicotine polacrilex gum containing 4 mg of nicotine (n = 92) or a placebo (n = 90). The number of participants abstinent at 2-year follow-up was 41 (44.6%) of 92 in the nicotine group vs 28 (31.1%) of 90 in the placebo group. Abstinence rates for daily nicotine gum users (n = 64) at 12 months and again at 24 months remained 48.4%, as compared with 26.1% and 31.9% for the daily placebo gum users (n = 69). Of participants with a high nicotine-dependence score, those allotted to the nicotine group rather than to the placebo group were 13 times more likely to be abstaining at the 2-year follow-up. Use of nicotine polacrilex gum, therefore, can substantially aid in stopping smoking, particularly among highly dependent smokers.