【Abstract】 Objective To observe the effect of pioglitazone on cell proliferation, apoptosis and tumor necrosis factor-α (TNF-α) expression in rat peritoneal mesothelial cell (RPMC) stimulated with lipopolysaccharide (LPS). Methodology RPMCs were isolated after enzymatic digestion, cultured, and identified by phase contrast inverted microscope and immunocytochemistry method. MTT method was used to observe the effects of lipopolysaccharide (10ng/ml) and pioglitazone (5, 10, and 20μmol/L) on cell proliferation. Apoptosis rate was determined by flow cytometry, and TNF-α in culture medium was assayed by ELISA. Results LPS inhibited cell proliferation significantly (P＜0.01), and induced apoptosis (P＜0.01) and TNF-α expression (P＜0.01) in RPMC. These changes could be partially reversed by 5～20μmol/L pioglitazone (P＜0.01). Conclusion Pioglitazone reverses the inhibition of cell proliferation, the increase of apoptosis rate, and the higher expression of fibrosis cytokine TNF-α in RPMCs induced by LPS, through which peritoneal damage is repaired and the inflammation is improved. Therefore, our experimental evidences suggest the prevention and treatment approaches for peritoneal mesothelial cell injury and dialysis-related peritonitis.