Abstract: Abstract　Objective: To investigate the role of hMLH1 and hMSH2 gene expression in cisplatin resistance of human ovarian cancer ( OC ). Methods: The chemosensitivity of OC to cisplatin was determined with an MTT assay. Hoechst fluorescence analysis was used to test the DDP-induced sensitivity and apoptosis of the drug-fast cells. hMLH1 and hMLH2 expression at the transcriptional and translational levels in the DDP-sensitive SKOV3 cells and DDP-resistant SKOV3/DDP cell line were measured by reverse transcription polymerase chain reaction ( RT-PCR ) and Western blot analysis, respectively. Results: The apoptotic rate of the cell SKOV3/DDP line was markedly lower than that of the SKOV3 cells after cisplatin administration at the same concentration. Both the mRNA and protein levels of hMLH1 and hMSH2 were significantly higher in the SKOV3 than in SKOV3/DDP cells. Conclusion: Cisplatin induces the apoptosis of the SKOV3 and SKOV3/DDP cell lines. In the drug-tolerant SKOV3/DDP cells, the low expression of the hMLH1 and hMSH2 genes may be the major cause of the occurrence of cisplatin resistance.