41 patients, who underwent maxillo-facial surgery received mostly for 10 days the instant formula diet Fresubin liquid during the postoperative period. The diet was applied via a nasogastric tube. Feeding had to be interrupted in 5 patients (12.5%) due to nausea, vomitus and diarrhoea. The incidence of nausea, diarrhoea and eructuation with short duration was in relation to the days of tube feeding 0.9%. The mean frequency of defacation was 0.7/24 hours. Giving about 25 kcal/kg body weight/day we did not see significant changes of body weight, of the Na, K and Ca serum concentrations or other effects. Caused by operation and anesthesia we found a decrease of the hemoglobin, hematocrit, albumin in the serum, and an increase of SGOT and SGPT.