In the first 5 postoperative days following abdominoperineal resection, 2 groups of 5 patients were treated by infusion therapy following 2 schedules: 11.9 cal/kg per day and 0.042 g of N/kg per day, and 53.8 cal/kg per day and 0.244 g of N/kg per day. N balance was determined, and the wound collagen content was evaluated by biopsies carried out on the 2nd, 3rd, 4th, 5th, 6th, 9th, 12th and 15th postoperative days. In group 2 patients N balance was rather equilibrated and the quantity of collagen in the granulation tissue was higher than in group 1. Postoperative parenteral hyperalimentation spares a good quantity of N and can facilitate wound healing.