Adenomatous polyps (hereinafter referred to as adenomas) are known precursors of colorectal cancer. Cigarette smoking has been associated with adenomas but not with colorectal cancer, while alcohol and fat intake have been associated with both adenomas and cancer in some studies. Approximately 30 percent of patients with resected adenomas develop another adenoma within three years. This case-control study explores the association of cigarette smoking with adenoma recurrence. Between April 1986 and March 1988, we administered a questionnaire to colonoscoped patients aged 35 to 84 years in three New York City (NY, USA) practices. We compared 186 recurrent polyp cases (130 males, 56 females) and 330 controls (187 males, 143 females) who had a history of polypectomy but normal follow-up colonoscopy, by cigarette-smoking pack-years adjusted for possible confounders. Risk for a metachronous or recurrent adenoma was significantly greater in the highest quartile of smokers than in never-smokers among both men (odds ratio [OR] = 1.8, 95 percent confidence interval [CI] = 1.0-3.4) and women (OR = 3.6, CI = 1.7-7.6). Adjustment for time since smoking cessation reduced risk only slightly, as did adjustment for dietary fat intake, which itself remained significant. No association was found between alcohol intake and risk of recurrence. Cigarette smokers appear to have an elevated risk of adenoma recurrence that is not eliminated entirely by smoking cessation. Intervention trials that use adenoma recurrence as an endpoint should take smoking into account.