The effects of four day periods of infusions of 600 gm/24 hours glucose and 600 gm/24 hours of a combination of glucose, fructose, and xylitol were compared. This study was performed during total parenteral nutrition of twelve postoperative patients with major complications. The mean plasma glucose level was significantly lower during the infusion of the combination of sugars (154.2+/-19.5 mg/100 ml versus 193.9+/-15.0 mg/100 ml[p is less than 0.005). Furthermore, the required dosage of exogenous insulin was significantly lower (18.9+/-12.3 units/day versus 43.7+/-19.7 units/day [p is less than 0.01). Mean renal carbohydrate losses were 0.85 per cent during glucose infusion and 1.7 per cent during infusion of the combination. The influence of both infusion regimes on values for pH, base excess, lactate, pyruvate, free fatty acids, insulin, sodium, potassium, chloride, magnesium, phosphorus, bilirubin, alkaline phosphatase, SGOT, and SGPT 0.85 has been investigated. No clinical side effects were observed. It is concluded that the administration of the investigated combination of glucose, fructose, and xylitol is justified in patients in whom hyperglycemia during infusion of glucose alone is difficult to control with insulin.