In 24 diabetic children treated with insulin xylitol was used as a sugar substitute for four weeks in an amount of 30 gms/day. In one case only the xylitol application was terminated before the end of the dietetic period because of diarrhoea. The other children tolerated xylitol fairly well, three of the children found the polyol too sweet. Because of incomplete data, the values of only 18 children were compiled. A significant increase of serum uric acid concentration measuring 1 mg/100 ml was the main side effect of xylitol usage. This effect was favoured by the fact that diabetic children do not use sucrose. As was shown earlier, a sucrose free period is the precondition for the possibility to find a xylitol induced hyperuricemia. In metabolically healthy children the existence of a sucrose induced hyperuricemia is also to be expected, this xylitol effect is, therefore, obviously without pathophysiological significance. Xylitol is suited for use as a sugar substitute in diabetic diet and in caries prophylaxis if the limited dose is observed.