Abstract: Objective To investigate the correlation between S100 calcium-binding protein A4(S100A4）and cisplatin-based chemotherapy resistance in ovarian cancer. Methods The expression of S100A4 in 60 ovarian cancer tissues was identified by immunohistochemistry method.RT-PCR and Western blot were used to evaluate the S100A4 mRNA and protein level respectively in platinum sensitive A2780 cell line and platinum resistant CP70 cell line.MTT assay was performed to determine the 50% inhibitory concentration (IC50) to cisplatin in A2780 and CP70 cells. MTT assay was performed to determine the 50% inhibitory concentration(IC50) to cisplatin in A2780 and CP70 cells. MTT assay was performed to determine the 50% inhibitory concentration(IC50) to cisplatin in A2780 and CP70 cells. ResultsS100A4 was located in the cytoplasm and nucleus.The positive rate of S100A4 protein in platinum resistant cases was higher than that in patients sensitive to platinum chemotherapy.The expression of S100A4 mRNA and protein were significantly higher in CP70 cells than that in A2780 cells.The IC50 was 20.54 μmol/ml in A2780 cells and 56.23 μmol/ml in CP70 cells，respectively. Conclusion High S100A4 expression predicts cisplatin-based chemotherapy resistance in ovarian cancer.