Preoperative antibiotic prophylaxis is known to significantly reduce the incidence of postoperative wound infection in elective colorectal surgery, and is a recognized part of surgical management. Antibiotics are usually given systemically or orally, or by a combination of the two routes. Local antibiotic delivery to the wound site using an implanted, reabsorbable, gentamicin-containing collagen sponge is a novel concept. We compared postoperative wound infection rates in 221 colorectal surgery patients randomized to receive systemic gentamicin/metronidazole with (Group I, n = 107) or without (Group II, n = 114) the gentamicin-collagen sponge. The two patient groups were identical on the basis of demographics and operations undergone. The postoperative wound infection rate was significantly lower in Group I patients than Group II 5.6% (6/107) and 18.4% (21/114), respectively (p <0.01). The mean duration of hospital stay was 13.8 days in Group I and 16.3 days in Group II, which did not represent a statistically significant difference. The gentamicin collagen sponge was well tolerated and no adverse events were reported that were attributable to its use. This new method for delivering gentamicin directly to the operative site may represent a significant method for reducing postoperative wound infection rates to levels lower than those currently achieved with systemic antibiotics alone