Functional stability of the peritoneal membrane is necessary for maintenance of peritoneal dialysis (PD) as a therapeutic option. Few studies have investigated this issue in children. We evaluated the peritoneal membrane solute transport capacity longitudinally in 26 children (mean age 11.0+/-5.5 years) receiving long-term PD. Each patient underwent a standardized peritoneal equilibration test on two occasions (mean interval between studies 19.8+/-5.9 months) to determine solute dialysate to plasma (D/P) ratios, dialysate glucose to initial dialysate glucose (D/D(0)) ratios, and mass transfer area coefficients (MTAC). The correlation of transport capacity with peritonitis history was also assessed. No significant change in MTAC, D/P, or D/D(0) values were found when comparing original and follow-up data of the group overall. However, transport of creatinine and glucose was significantly (P<0.05) greater in the peritonitis group compared with the group without peritonitis, and differences in the change over time between the peritonitis groups was significant for MTAC creatinine (P=0.035) and D/D(0) glucose (P=0.020). In summary, this experience demonstrates functional stability of the peritoneal membrane in pediatric patients receiving PD. However, follow-up assessments of peritoneal solute kinetics may be necessary in patients with a history of peritonitis in order to permit early identification of those who may be at risk for ultrafiltration failure and sclerosing peritonitis.