This study determined whether higher dose nicotine patches are more efficacious than lower dose patches among heavy smokers. A randomized double-blind study compared 0, 21, 35, and 42 ing/day of a 24-h patch in 1039 smokers (≥30 cigarettes/day) at 12 clinical sites in the USA and one in Australia. Daily patches were used for 6 weeks followed by tapering over the next 10 weeks. Weekly group therapy occurred. Biochemically validated self-reported quit rates at 6, 12, 26, and 52 weeks post-cessation were measured. Quit rates were dose-related at all follow-ups (p < 0.01). Continuous, biochemically verified abstinence rates for the 0, 21, 35, and 42 mg doses at the end of treatment (12 weeks) were 16, 24, 30, and 39%. At 6 months, the rates were 13, 20, 20, and 26%. Among the 11 sites with 12 month follow-up (n = 879), the quit rates were 7, 13, 9, and 19%. In post-hoc tests, none of the active doses were significantly different from each other at any follow-up. The rates of dropouts due to adverse events for 0, 21, 35, and 42 mg were 3, 1, 3, and 6% (p = n.s.). Our results are similar to most prior smaller studies; i.e., in heavy smokers higher doses increase quit rates slightly. Longer durations of treatment may be necessary to show greater advantages from higher doses.