A controlled, randomized study of the efficacy of a plastic wound ring drape (Opdrape, Triplus) to prevent contamination and infection in elective colorectal operations is reported. Seventy patients were operated upon with the wound ring drape and 70 patients without. All patients received preoperative systemic antibiotic prophylaxis. Abdominal wound infection was observed in seven of 70 (10 per cent) patients with the wound ring drape and six of 70 (9 per cent) without (N.S.). An operative swab for bacteriologic evaluation was obtained from 85 per cent of the wounds. There was no evidence that the drape protected the wound from contamination with intestinal bacterial flora. It was concluded that the wound ring drape prevents neither contamination nor infection.