40 patients, who underwent maxillo-facial surgery, were fed with the native physiological diet Nutro-Drip via nasogastric tubes for 10 days. Due to intolerance in 5% of the patients, the nutrition had to be interrupted. The other patients received 1500-2500 ml Nutro-Drip per 24 h (= 1605--2675 kcal = 6780-11300 J). Transient side effects were: diarrhoe 3,8%; nausea 0,8%; eructation and/or heartburn 1,1%; squeezing of the stomach 1,1%. In these patients nutrition with Nutro-Drip was not interrupted. The mean frequency of defecation was 0,81/day. There were no significant changes in body weight, serum electrolytes, water balance, blood sugar, liver enzymes, serum cholesterol, and acid-base balance during the feeding with Nutro-Drip. Immediately after surgery there was a statistically significant decrease in potassium, protein, and albumin levels in the serum with the tendency to normal values during Nutro-Drip feeding. During the postoperative period the urea content of the serum increased continuously without altering creatinin levels in the serum. Nutro-Drip seems to be very suitable for tube-feeding in patients with normal gastro-intestinal tract.