This study was designed to analyze the complex morphologic and functional effects of dialysis solutions on peritoneum in a rat model on chronic peritoneal dialysis. Peritoneal catheters were inserted into 10 male, Wistar rats and the animals were dialyzed twice daily for 4 weeks with 4.25% Dianeal. During the study we observed two opposite effects: healing of the peritoneum after catheter implantation--decreased cell count in dialysate, decreased permeability of the peritoneum to glucose and total protein, increased volume of drained dialysate; and damage to the membrane due to its exposure to peritoneal dialysis solution--increased hyaluronic acid levels in dialysate, a tendency of the peritoneum to thicken when compared to non-dialyzed animals. Our rat model of CAPD may be used for quantitative and qualitative assessment of the effects of peritoneal dialysis solution on the peritoneum during chronic dialysis.