Objectives. An analysis of gender differences in smoking cessation was conducted among 3923 participants in the Special Intervention group of the Lung Health Study. This report focuses on gender differences in sustained quit rates at 12 and 36 months. Methods. Special Intervention participants were offered a 12-session, 12-week smoking cessation program using nicotine gum and were followed for 3 years. Self-reported smoking status was validated with carbon monoxide and salivary cotinine. Results. Men had higher sustained quit rates at 12 and 36 months; gender differences were found in baseline variables that also predicted sustained abstinence; and controlling for selected baseline variables reduced the association between gender and sustained abstinence. When other variables were controlled, gender predicted sustained abstinence at 36 months (odds ratio [OR] = 1.24, 95% confidence interval [CI] = 1.04, 1.48) but not 12 months (OR = 1.08, 95% CI = 0.92, 1.27), reflecting more late relapse among women. Conclusions. Demographics and smoking history were more important than gender per se in sustained smoking cessation in the Lung Health Study. Programs tailoring smoking cessation by gender need to include coping skills for problems associated with less education and social support and for improving persistence with quit attempts.