BACKGROUND: Colorectal surgery may lead to infections because despite meticulous aseptic measures, extravasation of microorganisms from the colon lumen is unavoidable. STUDY DESIGN: A prospective, randomized study was performed between January 2010 and December 2010. Patient inclusion criteria were a diagnosis of colorectal neoplasms and plans to undergo an elective curative operation. Patients were divided into 2 groups: Group 1 (intra-abdominal irrigation with normal saline) andGroup 2 (intraperitoneal irrigation with a solution of 240 mg gentamicin and 600 mg clindamycin). The occurrence of wound infections and intra-abdominal abscesses were investigated. After the anastomosis, a microbiologic sample of the peritoneal surface was obtained (sample 1). A second sample was collected after irrigation with normal saline (sample 2). Finally, the peritoneal cavity was irrigated with a gentamicin-clindamycin solution and a third sample was obtained (sample 3). RESULTS: There were 103 patients analyzed: 51 in Group 1 and 52 in Group 2. There were no significant differences between the groups in age, sex, comorbidities, or type of colorectal surgery performed. Wound infection rates were 14% in Group 1 and 4% in Group 2 (p = 0.009; odds ratio [OR] 4.94; 95% CI 1.27 to 19.19). Intra-abdominal abscess rates were 6% in Group 1 and 0% in Group 2 (p = 0.014; OR 2.14; 95% CI 1.13 to 3.57). The culture of sample 1 was positive in 68% of the cases, sample 2 was positive in 59%, and sample 3 in 4%. CONCLUSIONS: Antibiotic lavage of the peritoneum is associated with a lower incidence of intra-abdominal abscesses and wound infections. (J Am Coll Surg 2012;214:202-207. (C) 2012 by the American College of Surgeons)