This population-based case-control study examined the association between selected nutrients, foods, and diet behaviors and bladder cancer. Bladder cancer cases (n = 262) were identified from the Surveillance, Epidemiology, and End Results Program cancer registry for western Washington, and controls (n = 405) were identified through random digit dialing. Cases were diagnosed between January 1987 and June 1990, and eligible subjects were Caucasian, aged 45-65 years, and residents of King, Pierce, or Snohomish counties. Subjects completed a self-administered, 71-item food frequency questionnaire and a structured telephone interview. Analyses were conducted by logistic regression analysis and included adjustment for age, sex, smoking (current, former, never), and county. Odds ratios and their 95% confidence intervals for highest versus lowest level of intake were examined. An inverse association was found between the risk of bladder cancer and dietary retinol (odds ratio (OR) across quartiles: 1.00, 1.09, 0.97, and 0.52; 95% CI 0.29-0.97; trend p value = 0.03) and dietary vitamin C (OR across quartiles: 1.00, 0.96, 0.67, and 0.50; 95% CI 0.28-0.88; trend p value = 0.009), adjusted for calories. The use of multivitamin supplements daily over the 10-year period ending 2 years before diagnosis versus no use was associated with a decreased risk of bladder cancer (OR = 0.39; 95% CI 0.24-0.63) as was use of supplemental vitamin C (OR for > 502 mg/day over the 10 years vs. none = 0.40; 95% CI 0.21-0.76). Increased intake of fruit was associated with a decreased risk of bladder cancer (OR across quartiles: 1.00, 1.24, 0.72, and 0.53; 95% CI 0.30-0.93; trend p value = 0.01, adjusted for calories), while increased use of fried foods was associated with an increased risk of bladder cancer (OR across quartiles: 1.00, 1.51, 1.81, and 2.24; 95% CI 1.25-4.03; trend p value = 0.006). This study provides modest evidence that certain nutrients, foods, and supplementation may affect the incidence of bladder cancer.