Patients with gangrenous nonperforated appendicitis have a high risk of developing postsurgical infectious complications. The present prospective randomized multicenter study was performed to ascertain whether a single, intraoperative high dose (4 g) cefoxitin given intravenously effectively reduces infectious complications in these patients. The postsurgical infection rate in the treated group was 13.3% as compared to 41.9% in nontreated control patients. This reduction is statistically significant (p < 0.025). Cefoxitin given as a single dose of 4 g is a simple and safe treatment that effectively decreases postsurgical infectious complications in patients with nonperforated gangrenous appendicitis.