Abstract: Objective : To study the expression of extracellular signal-regulated kinase (ERK) in epithelial ovarian cancer and the effect of ERK kinase MEK1 inhibitor PD98059 on growth of the human ovarian cancer cell. Methods : Immunohistochemical method and western blot were employed in this study to detect distribution and quantity analysis of ERK protein, MTT assay was used to determine the suppressive effect of different concentration of PD98059 on ovarian cancer cell for 12, 24, 48 and 72 h. The apoptosis of ovarian cancer cell induced by PD98059 was detected by scanning electron microscope, transmission electron microscope and DNA-ladder electrophoresis. Results : The expression of ERK was higher in cancer than in normal ovarian tissue and benign ovarian tumor (P<0.01). It was significantly higher for ovarian cancer in stage Ⅲ and Ⅳ than in stage Ⅰ and Ⅱ(P<0.05). The PD98059 suppressed the proliferation of ovarian cancer cell in a dose and time-dependent manner. The apoptosis of ovarian cancer cell induced by PD98059 appeared when PD98059 was at 100μM for 72 h. Conclusion : The over-expression of ERK may play an important role in initiation and development of the epithelial ovarian cancer. PD98059 could suppress the proliferation and induce the apoptosis of ovarian cancer cell.