Peritoneal clearances and dialysate protein losses occurring in paediatric patients undergoing different continuous cycling peritoneal dialysis (CCPD) regimens have not been well defined. We, therefore, evaluated 10 children aged 15.8 +/- 2.5 (SD) years who were maintained on home peritoneal dialysis for 20.5 +/- 10 months. All patients had at least 3 months of CCPD. The patients were admitted to the Clinical Research Center for 48 hours and allocated to five different dialysis protocols. In protocol I, the frequency of exchanges was 10 per 10 hours; in Protocol II it was 5 per 10 hours; and in Protocol III it was 3 per 10 hours. Protocol II D and III D had, in addition, a daytime dwell of one-half the night-time volume. A 1.5% glucose dialysate solution was used for night-time dialysis, and 4.25% glucose dialysate solution for the daytime dwell. The mean inflow dialysate volume per exchange was 36.7 +/- 5.6 ml/kg body weight and was constant in each patient for each study protocol. BUN and creatinine clearances for each protocol were calculated and dialysate protein losses were measured. The data indicate that hourly night-time dialysis (Protocol I) provides best solute clearance. A daytime dwell further enhances the total solute clearance and should be used preferably in anuric patients. Residual urine output contributes significantly to the total solute clearance. Protein losses are maximum with low-frequency exchanges and a daytime dwell. No significant differences in the serum albumin concentrations were found during the different protocols; however, the long-term effect of the protein loss on the nutritional status of the patients requires further evaluation.