A case-control study of colorectal cancer in relation to dietary, smoking, and drinking habits was undertaken in Saitama Prefecture, Japan. The study was based on 181 newly diagnosed cases of adenocarcinoma of the colorectum at a single institution and 653 general population controls. Dietary habits were investigated on the basis of the intake of 12 foods and 12 food groups in a food intake frequency questionnaire, together with individual food preferences. Preference for salty foods was positively related to the risk of both colon and rectal cancer, and the consumption of seaweed was inversely related to these cancers, both with a dose-response relation. Cigarette smoking was inversely related to colon cancer risk, but not to rectal cancer risk. Alcohol intake tended to be associated inversely with colon cancer, but not with rectal cancer. In the multiple logistic regression, preference for salty foods (positively) and the consumption of seaweed (inversely) were independently related to both colon and rectal cancer risks.