Seventy-eight smokers trying to quit were randomly assigned to 0-, 0.5-, 2- and 4-mg doses of nicotine gum and tracked for 9 months. In the 1st week of abstinence, self-administration of gum did not differ by dose (4 mg = 2 mg = 0.5 mg = 0 mg). Higher doses did not more effectively suppress withdrawal than lower doses nor induce more accurate nicotine identification (4 mg = 2 mg = 0.5 mg greater than 0 mg). Higher doses slightly increased ratings of adverse effects in the 1st week (4 mg greater than 2 mg greater than 0.5 mg greater than 0 mg). Over the next 6 months, the two higher doses appeared to support more gum self-administration than the two lower doses (4 mg = 2 mg greater than 0.5 mg = 0 mg) in the subsample of long-term quitters (n = 20). Our results suggest the dose-response curves differ for nicotine gum's reinforcing, withdrawal-suppression and self-reported effects.