The relationship of adenomatous polyps of the sigmoid colon with cigarette smoking and alcohol use was investigated in male self-defense officials in Japan. In the comparison between 116 cases and 930 controls, total ethanol intake was not at all associated with the risk of adenomatous polyps, but cigarette smoking was strongly related to adenomatous polyps. After adjustment for total ethanol intake, body mass index and rank, odds ratios (and 95% confidence interval) for the categories of 0, 1-399, 400-799, and 800 or more cigarette-years were 1.0 (referent), 2.3 (1.1-4.6), 2.9 (1.5-5.4) and 3.2 (1.6-6.5), respectively. Among five alcoholic beverages (sake, shochu, beer, whiskey including brandy, and wine), only whiskey consumption was weakly related to the risk of adenomatous polyps. Because the present findings disagree with an earlier observation on self-defense officials, we examined the association with smoking and alcohol use separately for small (less than 5 mm) and large (greater than or equal to 5 mm) adenomas, combining data from these two studies. Cigarette smoking was more strongly associated with small adenomas while the positive association with certain alcoholic beverages were largely confined to large adenomas. These findings suggest that cigarette smoking and alcohol use may be linked with the development of adenoma at different stages of colon tumorigenesis.