A prospective randomized investigation was undertaken, involving 168 consecutive patients undergoing laparotomy for conditions accompanying bacterially contaminated peritoneal cavities, to evaluate the effectiveness of povidone-iodine irrigation of the peritoneum in preventing the development of intra-abdominal abscesses. In the treatment group irrigated with povidone-iodine solution, 0.1 per cent available iodine, one of 80 patients had an abscess, 1.3 per cent, while, in the saline solution irrigated control group, nine of 88 patients had abscesses, 10.2 per cent, p less than 0.05. Although the serum iodine levels were elevated 24 hours after intraperitoneal irrigation with povidone-iodine solution, iodine levels returned to near normal by 72 hours. Thyroxine levels showed no major changes. No complications resulting from the use of povidone-iodine were recognized.