Sclerosing encapsulating peritonitis (SEP) is recognized as a serious complication of continuous ambulatory peritoneal dialysis (CAPD). To date, in our hospital, 12 cases of SEP have been successfully treated by active intervention. The development of SEP was observed in these patients after removal of a peritoneal catheter. SEP was relieved by steroid administration in 3 of these patients, and by total parenteral nutrition (TPN) performed after exploratory laparotomy in 1 patient. In the remaining 8 patients, SEP was relieved by total intestinal enterolysis. In patients who underwent total intestinal enterolysis, the severity of encapsulation and adhesion varied. White, rigid encapsulation was observed in 4 patients who had been treated by peritoneal dialysis (PD) for less than 10 years. Seemingly normal serosae were observed under the capsules, and total intestinal enterolysis was easily performed in these patients. In the patient who underwent renal transplantation, more severe intestinal adhesion was observed, although the duration of PD was limited to 70 months and the intestinal serosae were seemingly normal. These findings were considered specific to SEP developing after immunosuppressant administration. In 3 patients who had undergone PD for more than 10 years, degeneration of the visceral peritoneum was observed, together with an ill-defined boundary between the capsules and the serosae. Therefore, total enterolysis was performed in these patients, including a wide area of the muscular layer. Furthermore, calcification was observed in several regions, where the capsules were severely adherent to the parietal peritoneum. The post-operative course for all 8 patients was satisfactory, and these patients finally returned to their previous social activities. We conclude that when SEP symptoms are not improved by steroid administration or TPN, active total intestinal enterolysis should be performed. However, it is absolutely important to avoid inducing anastomosis or impairing the intestine.