This is the first report on an occupational bladder cancer in Korea. The ease is 41 years old man who worked as a dyer for 17 years at two dyeing factories, which handled nylon and polyester fabrics in Taegu. He was exposed to many kinds of dyes during weighing, mixing, dissolving and dyeing processes. Among many kinds of acid, disperse and direct dyes that he has been exposed to, several dyes have confirmed to contain benzidine-based dyes, one was o-tolidine-based dye, and one was o-dianisidine-based dye. He visited a hospital due to the gross hematuria and urinary frequency in June, 1998, and he had radical cystectomy with ileal conduit diversion. He had smoked a half-pack of cigarette for 20 years. The main risk factor of bladder cancer is smoking, however, he was relatively a light smoker than usual Korean men. He was exposed to the definite occupational carcinogen even though the level was relatively lower than that of dye manufacturers. His age was younger than the prevalence age of bladder cancer caused by smoking. These evidences support that the dyer' s bladder cancer could be related to the occupational exposure to benzidine-based dyes.