Twelve percent (five of 41) of men over 50 years of age under-going inguinal herniorrhaphy required postoperative catheterization. No urinary tract infections developed. Eighteen percent (five of 36) of similar patients treated by inlying catheter during the operation only required later postoperative catheterization. No urinary tract infections developed. Of a third group of similar patients on whom the catheter was allowed to remain in place for 24 hours, no further catheterizations were required. Three developed bacteriuria, which was not present before operation, all of which cleared with appropriate antibiotics. If the surgeon intuitively anticipates the need for postoperative catheterization where such catheterization may not be possible under ideal circumstances, an inlying catheter inserted under ideal conditions in the operating room is recommended for 24 hours.