The authors prospectively studied the incidence of cancers of the colon and rectum in 106,203 men and women, both white and black, who supplied data at northern California Kaiser Permanente facilities about use of alcoholic beverages in 1978-1984. Analysis controlling for age, sex, race, body mass index, coffee use, total serum cholesterol, and education showed a positive association of alcohol use to both types of cancer, which was stronger for rectal cancer (trend test, p = 0.03) than for colon cancer (trend test, p = 0.11). When persons with a daily intake of three or more drinks were compared with abstainers, relative risk for rectal cancer was 3.17 (95% confidence interval (CI): 1.05-9.57) and relative risk for colon cancer was 1.71 (95% CI: 0.92-3.19). Women with a daily intake of three or more drinks had a relative risk for colon cancer of 2.56 (95% CI: 1.03-6.40) compared with 1.16 (95% CI: 0.46-2.90) for men. Among drinkers, preference for wine, beer, or hard liquor had no significant independent relation to either type of cancer; those who preferred beer were at slightly greater risk of rectal cancer, but those who preferred wine were more likely to develop colon cancer. These data suggest that total alcohol use, but no one specific beverage type, is associated with increased risk of rectal cancer.