One chronic uraemic patient was treated with intermittent peritoneal dialysis. During the 9th month decreasing of ultrafiltration and increasing of the blood level of low-molecular weight substances was observed. Laparotomy was performed twice because of increased intraperitoneal bleeding. During the operation peritoneal thickening, intestinal adhesion and diffuse bleeding was noticed. The patient died because of ileus. The most probable cause of sclerosing peritonitis was due to the formalin solution, which was used for the disinfection of the Tenckhoff catheter. The causes and prevention of sclerosing peritonitis has been summarised.