To compare the effects of low-calcium and high-calcium dialysate in stable ESRD patients on peritoneal dialysis (PD).Dialysate containing 2.5 mEq/l and 3.5 mEq/l calcium in combination with oral calcium salts as phosphate binders were evaluated.Tertiary-referral university hospital.Fifteen patients (6 male, 9 female) on low-calcium (2.5 mEq/l) and 15 patients (6 male, 9 female) on high-calcium (3.5 mEq/l) dialysate were studied for 6 months. All patients received calcium acetate or calcium carbonate to control hyperphosphatemia before the study.Serum calcium, phosphorus and albumin did not differ before and after between the two groups. Three patients in low-calcium and five in high-calcium group developed hypercalcemia. Three in low-calcium group and four in high-calcium group required sucralfate to control hyperphosphatemia and hypercalcemia. Mean dose of elemental calcium was 1152 mg/day in low-calcium group and 790 mg/day in high-calcium group. A negative correlation (r = -0.82, p < 0.005) was observed between serum calcium and PTH at the end of study period in the low-calcium group. No such relationship was observed in the high-calcium group.Degree and frequency of hypercalcemia appeared similar with low-calcium and high-calcium dialysate in peritoneal dialysis patients.