Sclerosing encapsulating peritonitis (SEP) is a rare yet serious complication in patients with continuous ambulatory peritoneal dialysis (CAPD). Incidence and prevalence of this syndrome have been defined in some large populations and a few single-centre experiences, but there is no satisfactory estimate of the comparative incidence of dialysis related SEP. The pathogenesis of SEP still remains uncertain, but there could be various causative factors. The diagnosis of SEP remains based on clinical suspicion confirmed with radiologic and/or pathologic findings. The possible variable etiologies and probable distinct pathways leading to this syndrome may make a uniform therapeutic approach unlikely. To determine the prevalence, etiologic factors, clinical features, effect of dialysis duration, and outcome of SEP in Korea, patients undergoing CAPD who developed SEP were retrospectively studied in five University Hospital dialysis centres with large numbers of CAPD patients in Korea. Out of a total 3888 CAPD studied patients between January 1981 to December 2002 in those five medical centres, 31 cases developed SEP with the overall prevalence 0.8%. There were 15 men and 16 women. The mean age of these patients was 44.0 +/- 9.8 years old. The mean duration of CAPD before SEP was 70.3 +/- 41.9 months (range 9-144 months) and 67.8% of patients (21/31) had been on CAPD more than 4 years. Peritonitis, including one fungal peritonitis, was the main cause of SEP in 25 cases (80.6%). Seventy percent of these cases used beta-blocker and the mean duration of the usage was 61.7 +/- 47.6 months. Seven cases were surgically treated and others were treated conservatively with intermittent total parenteral nutrition. The mortality rate was 25.8%. In conclusion, SEP is a serious life threatening complication of CAPD, and most cases had long-term peritoneal dialysis (PD) duration more than 4 years. To reduce the incidence of SEP, careful monitoring may be needed especially in patients with long-term CAPD and peritonitis.