We examined the relationship between occupation and bladder cancer risk using data obtained from interviews conducted with 2,100 white males with bladder cancer and 3,874 population controls during the National Bladder Cancer Study, a population-based, case-control study conducted in 10 areas of the United States. The strongest evidence of increased risk among white men was observed for painters, truck drivers, and drill press operatives. For painters, the overall relative risk was 1.5 [95% confidence intervals (CI) = 1.2-2.0]. Among painters who started working prior to 1930, a significant trend in risk with increasing duration of employment as a painter was apparent; the relative risk for such painters employed 10 or more years was 3.0. For truck drivers and drill press operatives, overall risks were 1.3 (CI = 1.1-1.4) and 1.4 (CI = 0.9-2.1), respectively. We observed a significant, positive trend in risk with increasing duration of employment in each of these occupations, with relative risks peaking at approximately two for long-term workers. Excess risks were also observed for workers in several other occupations. In all, we estimate that 21%-25% of bladder cancer diagnosed among white men in the United States is attributable to occupational exposures.