Short-term urinary bladder drainage with the use of urethral Foley catheters is practiced frequently in hospitals throughout the country. We studied the urethral and bladder cellular proliferation after exposure to latex, silicone-coated latex, and 100% silicone catheters. Fifty-one male patients were studied; no differences in acute cellular reaction could be detected among the three different catheter materials. Promotion of all-silicone products in hospital use may be unwarranted.