The research on the effectiveness of nicotine gum as a treatment for smoking was reviewed through a meta-analysis of 33 studies. The differential effectiveness of experimental (nicotine gum) versus control (placebo and no gum) groups at both short- and long-term follow-up was indexed as d, the mean effect size. These effect sizes were contrasted within each brief and intensive treatments. Nicotine gum was superior to placebo and no-gum controls at both intervals with the intensive strategies, but the gum was effective only at short term for the brief treatments. Results show that the positive effects of nicotine gum in smoking treatment are a function of an interaction between the gum's pharmacological properties and the effectiveness of intensive treatment strategies. The theoretical and clinical implications of the results are discussed.