The relationship between coffee drinking and risk of bladder cancer was assessed with the use of data from a case-control study of bladder cancer. Incident cases (2,982) and general population controls (5,782) were interviewed. Overall, the relative risk (RR) of bladder cancer for subjects who had ever drunk coffee was estimated as 1.4 (95% confidence interval = 1.1-1.8). There was no consistent relation between the RR estimate and the current consumption level. Among men who drank coffee, those who drank more than 49 cupfuls of coffee per week had an apparent excess in risk, but women who drank that much had an apparent deficit in risk.