Abstract: ObjectiveTo investigate the expression and role of HSP27 in Cisplatin-sensitive ovarian cancer cell OV2008 and Cisplatin-resistant ovarian cancer cell CI3K. Methods To examine expression of HSP27 gene in OV2008 cells and CI3K cells; siRNA and eukaryotic expression plasmid pEGFP- C1-HSP27were synthesized and transfected into human ovarian cancer cell by lipo2000, mRNA and protein expressions of HSP27 at different times after transfection were measured by real-time RT- PCR and Western blot, and the drug sensitivity to Cisplatin was detected by MTT and flow cytometry. Results (1) The expression of protein and mRNA on HSP27 in CI3K cells were significantly higher than those in OV2008 cells, the differences are significant (P<0.05). (2) Transfection of siRNA 48 h later, the 50% inhibition concentration (IC50 ) to Cisplatin of CI3K transfected with siRNA was obviously lower than that of empty-vector transfected cells and untransfected cells (P<0.05). Transfection with HSP27 full length plasmid p-HSP27 48 h later, the IC50 of OV2008 to Cisplatin was obviously higher than that of empty-vector transfected cells and untransfected cells (P<0.05). (3) Transfection of plasmid siRNA and p-HSP27 48 h, and then treated by Cisplatin 24 h later, the apoptosis rate of CI3K was increased［(41.42±0.68)%］, compared with empty vector (28.87±2.65)% and non-transfected CI3K cells(26.96±3.79）%(P<0.05); The apoptosis rate of OV2008 transfected with p-HSP27 (27.68±1.64)% was significantly decreased compared with empty vector transfected (47.52±3.12)% and non-transfected (49.32±2.31%) OV2008 cells(P<0.05). ConclusionHSP27 gene expression in CI3K and OV2008 cells could affect sensitivity to Cisplatin, suggesting that HSP27 gene might play an important role on Cisplatin-resistant in ovarian cancer.