OUTLINE: This is a randomized, multicenter study. Patients are stratified according to disease status (first occurrence vs recurrent disease). Patients are randomized to receive either oral ciprofloxacin or oral cephalexin 2 times a day for 3 days starting the night before resection. Patients who are allergic to penicillin or a cephalosporin receive oral co-trimoxazole 2 times a day for 3 days. All patients undergo complete resection of all bladder tumors. Patients are followed every 3 months for the first 2 years, every 6 months for the next 2 years, and at the end of the fifth year.