A prospective clinical trial was designed to evaluate the efficacy of postoperative jejunostomy feedings using high (44 percent) and low (15 percent) branched-chain amino acid elemental diet formulations compared with no jejunostomy feedings in a homogeneous surgical population. Twenty-eight patients undergoing radical cystectomy and ileal diversion were randomized to the high branched-chain amino acid formula (11 patients) or the low branched-chain amino acid formula (9 patients). Eight patients received a 5 percent dextrose in water solution intravenously and served as a control group. Mean caloric intake per day in each group was 1,543 calories, 1,697 calories, and 550 calories, respectively; whereas the mean nitrogen intake of each group was 6.5 +/- 2.1 g/day, 8.2 +/- 2.4 g/day, and 0 g/day, respectively. Mean weight changes were minus 0.7 percent, 0.7 percent, and minus 0.3 percent, respectively. The mean daily nitrogen balance was minus 1.6 +/- 3.5 g/day, minus 1.1 +/- 4.4 g/day, and minus 6.6 +/- 1 g/day (p less than 0.001). Five patients (25 percent) in the jejunostomy groups progressed to an oral diet more rapidly than the control group, but gastrointestinal complications occurred in 11 patients (55 percent). Immediate postoperative jejunostomy feedings resulted in improved nitrogen balance compared with the control group values, but no metabolic advantage was noted by infusing a high branched-chain amino acid formula. Improved return to normal gastrointestinal function was noted in 25 percent of jejunostomy patients, but the gastrointestinal complications noted limited the overall usefulness of this technique.