In order to investigate which component of dialysate is responsible for mesothelial cell damage, we studied the chronic cytotoxicity to mesothelial cells by using four types of solution. Four different types of solution (Ringer's solution, lactate, high-concentrate glucose, and 4.25% Dianeal) were prepared and injected into the abdominal cavity of five ddY-mice, 5 mL every day for one month. The monolayer of the mesothelial cells was carefully removed from the liver surface by the imprint technique. Then, the mesothelial cell damage was evaluated by using trypan blue staining and comparing the results. Trypan blue-stained cells in 100 mm2 were observed in 7.0% of the control, 15.4% of the Ringer's solution, 18.7% of the lactate, 23.2% of the high-concentrate glucose, and 22.4% of the 4.25% Dianeal group, respectively. The damaged cells were significantly (p < 0.05) greater in the 4.25% Dianeal group than in the control group, and those in the high-concentrate glucose group also appeared to be greater in number compared to the control group It is concluded from these results that damage to the mesothelial cells is induced by chronic exposure to high-glucose dialysate, and its pathogenesis is deeply related to high concentration of glucose.