Nicotine gum and transdermal nicotine have been shown to relieve withdrawal and double success rates over placebo in trials of smoking cessation. This study tested whether combining the two methods would relieve withdrawal more effectively compared to either treatment alone. Twenty-eight smokers served as their own controls in each of four conditions: active gum + active patch (double active), active gum + placebo patch (gum only active), placebo gum + active patch (patch active) and placebo gum + placebo patch (double placebo). This "double placebo" design controls sensory, psychological and ritual variables associated with each drug form. Withdrawal symptoms were rated four times daily for 3 days in each condition. Total baseline (smoking) withdrawal scores using visual analogue scales (VAS) averaged 101.1. During cessation, total withdrawal increased to 187.0 for the double placebo condition, 142.2 for the active gum/placebo patch treatment and 128.3 for the active patch/placebo gum treatment. The double active condition equalled smoking with score 99.2. All pairwise comparisons were significant (P < 0.001) except between the two single active conditions and between smoking versus the double active condition. Significant time-of-day effects by treatment on withdrawal were observed for the double placebo condition (P < 0.05) with less withdrawal in the morning. The findings suggest: 1) combining nicotine gum with transdermal nicotine may be superior to either treatment alone, 2) more symptoms may be nicotine specific (relieved by replacement) than previously thought.