Positive nitrogen balance and preservation of body weight and total proteins were demonstrated in 26 patients undergoing extensive upper gastrointestinal operations who were randomized to receive elemental diet by a needle catheter jejunostomy. Infusions were started immediately after operation and continued for 10 days. In 26 patients receiving enteral feedings and 22 intravenous control patients, mean cumulative 10 day nitrogen balance was +11.7 +/- 5.4 and -44.7 +/- 6.5 g, respectively (p = 0.0001). Enterally fed patients lost only 0.02 +/- 0.5 kg of weight compared with 3.8 +/- 0.3 kg in control patients. The only complications were diarrhea in 34 percent of the study patients and one broken catheter. It is probable that the nitrogen and body weight preservation provided by enteral hyperalimentation equals or exceeds that demonstrated for total parenteral nutrition in postoperative patients.