OBJECTIVE: To evaluate the effects of Tanshinone IIA (TSN) on oxidative stress and apoptosis of human peritoneal mesothelial cells (HPMCs) stimulated by peritoneal dialysis fluid (PDF). STUDY DESIGN: HPMCs cultured in vitro were divided into 4 groups to detect oxidative stress-related indices. After 48 hours the levels of malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione (GSH) in the supernatant were detected. On the other hand, HPMCs were divided into 5 groups to detect apoptosis-related cytokines. After 72 hours of treatment the mRNA and protein expressions of bax, caspase-3, and bcl-2 were detected by real-time polymerase chain reaction and Western blot, respectively. RESULTS: Compared with control group, the PDF group had a significantly increased level of MDA (p < 0.01) and decreased levels of SOD and GSH (p < 0.01). Compared with the PDF group, groups with TSN had a significantly decreased level of MDA (p < 0.01) and increased levels of SOD and GSH (p < 0.01). Compared with the control group, the PDF and H2O2 groups showed significantly increased mRNA and protein expressions of both bax and caspase-3 (p < 0.01), and decreased levels of bcl-2 (p < 0.01). Compared with PDF and H2O2 groups, PDF and H2O2 with TSN had significantly decreased mRNA and protein expressions of both bax and caspase-3 (p < 0.01) and increased expressions of bcl-2 (p < 0.01). CONCLUSION: TSN may downregulate PDF-induced high expressions of apoptosis-related cytokines by inhibiting oxidative stress of HPMCs and thus has a protective effect on peritoneal membrane. © Science Printers and Publishers, Inc.