Maltose or maltose in combination with fructose and xylitol was administered intravenously to eight healthy male subjects. Constant maltose levels could not be attained in the blood at an infusion rate of 0.125 g maltose/kg body-weight and hour. Maximal concentrations of maltose were found at the end of the infusion period. 8.6 +/- 1.2% of the administered radioactivity was excreted into urine within 8 hours. Regarding the enzymatically determined maltose and glucose, the maltose balance was more favorable with the loss of only 3--3.5% carbohydrates into urine. The highest oxidation rate of the administered maltose was 1.5 g maltose/human volunteer and hour. During the experimental period of 8 hours 7.4 g maltose, corresponding to 37% of the applied dosis of the disaccharid, has been oxidized to and excreted as 14CO2. Xylitol and fructose did not effect utilisation and balance of maltose. Only the urinary excretion of glucose was higher when the combined solution was applied. At a limited infusion rate (0.125 g maltose/kg body-weight and hour) maltose or the combined solution maltose--xylitol--fructose may be recommended for parenteral nutrition.