We studied the effects of bicarbonate dialysis solution (TB 1.36) on the peritoneum in our rat model of dialysis. Twenty-four male Sprague-Dawley rats were divided into two groups (n = 12 each). One group was dialyzed with standard 1.36% Dianeal PD-2 (L-group); the other group was dialyzed with TB 1.36 (B-group). After break-in dialysis after catheter insertion, the animals were dialyzed twice daily with 30 mL of the designated dialysis solution for four weeks. White blood cell count with differentials and microbiological culture of the dialysate were examined once a week to detect peritonitis. A peritoneal equilibration test (PET) was performed on the eighth and thirty-sixth days. The dialysate was obtained at 0, 2, and 4 hours; a blood sample was taken at 0 hour. Peritoneal tissue specimens were obtained after the second PET. Histological score was calculated based on the degree of thickening of the peritoneum. Five rats in L-group and three rats in B-group suffered from peritonitis. Two other rats in B-group had complications and did not complete the experiment. Therefore, seven rats from each group finished the experiment, and the PET data was analyzed. The peritoneal transport property of B-group did not change over time, while, in L-group it became less permeable on the thirty-sixth day. Fibrotic thickening of the peritoneum was observed in both groups, however, the histological score was slightly lower in B-group. These results suggest that the bicarbonate dialysis solution may be less harmful to the peritoneum.