We investigated the use of analgesics containing phenacetin or acetaminophen in 173 young women with urinary bladder cancer and 173 matched controls. The cases, who were 20 to 49 years old at the time of diagnosis of cancer, were 6.5 times more likely to report regular use of analgesics containing phenacetin at least one year before diagnosis than were their matched controls (odds ratio, 6.5; 95 per cent confidence interval, 1.5 to 59.2). Among the 15 women (13 cases and 2 controls) reporting regular use of phenacetin-containing drugs, 8 of the cases and 1 of the controls reported daily use for over one year (P = 0.04). Excessive use of analgesics containing acetaminophen was not reported. The increased risk of bladder cancer in young women who regularly used phenacetin-containing products remained present after adjustments for all other identified risk factors.