Multiple trauma is associated with altered metabolism, wasting of the lean body mass and compromised wound healing. Nutritional support is one way to improve the condition of these critically ill patients. We performed a prospective randomized study on the effect of early nutritional support in severely injured patients admitted to the Division of Traumatic Surgery, Siriraj Hospital between June 1992 and January 1994. Thirty-eight severe traumatic patients with ISS between 20-40 were randomly divided into control and study group. The 17 patients in the control group were treated in the conventional method with administration of hypo caloric intravenous regimen and supplement with oral diet as soon as the bowel function was returned. The 21 patients of the study group were fed either by enteral or parenteral feeding or both with an appropriate caloric and protein requirement as soon as hemodynamic status was stabilized. We found the study group had a lower mortality rate, a lower complication rate, a shorter period of ICU stay, and an earlier weaning from the ventilator than the control group. The study group also lost less weight than the control group. Nitrogen balance in the study group was significantly lower than the control group.