Peritoneal dialysis(PD) is an established method of dialysis for children at the end stage of renal failure. Among several problems associated with PD, peritoneal sclerosis is one of the most serious complications. We examined four children on PD who were diagnosed as having peritoneal sclerosis in 1997 and 1998. Three of these cases were switched to hemodialysis(HD) and one is now undergoing a switch from PD to HD. Although all of the four patients had a history of bacterial peritonitis, they had been maintained in a fairly good condition on PD. The mean duration of PD was 9 years(4-14 years). All cases were anuric and had been maintained on PD without any problems of peritoneal function. From these observations, we should consider peritoneal sclerosis even in patients with a good clinical condition during the long-term period of PD. We recommend serial peritoneal biopsies, at least at the time of peritoneal catheter changes, to check for peritoneal sclerosis. The patients who are diagnosed as having sclerotic thickening of the peritoneal membrane should be switched from PD to HD to prevent the occurrence of life-threatening peritoneal sclerosis.