Potential risk factors for bladder cancer were studied in a series of 76 male and 76 female bladder cancer cases and 238 male and 254 female controls who reported never having smoked. Risk factors included usual occupation, smoking by the spouse, sidestream smoke exposure at home and at work and in transportation, coffee drinking (caffeinated and decaffeinated), artificial sweetener use, body mass index, and a history of diabetes and high blood pressure. No association was found with spouse's smoking or reported sidestream smoke exposure, coffee drinking, artificial sweetener use, or a number of other variables; however, there was some indication that several occupations were overrepresented in the cases. A positive association was found with snuff use in women, but the numbers were small (three cases and one control). Restriction of the study to lifetime nonsmokers permitted the assessment of potential risk factors in the absence of potential confounding and interactive effects of smoking. The study had adequate statistical power to detect moderately small elevated risks due to the main factors examined.