The effects of commonly used analgesics like acetylsalicylic acid and paracetamol in therapeutic doses on the urinary tract epithelium [urothelium] of 24 healthy male volunteers, divided into two groups of 12 volunteers each, were studied by administering acetylsalicylic acid and paracetamol in doses of 300 mg and 500 mg three times a day respectively for 5 days. A control group of 12 healthy volunteers was put on pharmacologically inactive placebo tablets. A slight, but not significant, increase in the urinary excretion of epithelial cells, leucocytes and red blood cells was observed in two groups of healthy volunteers receiving analgesics in usual therapeutic doses