Introduction: The proto-oncogene HER2 plays a key role in the control of cellular proliferation. Its overexpression has been reported to be associated with a poor prognosis in cancer, particularly in breast cancer.Materials and Methods: In the present study, serum HER2 levels were investigated in patients diagnosed with epithelial ovarian cancer. Serum HER2 levels were detected by an ELISA commercial kit in 51 patients and 33 healthy individuals.Results: The mean serum HER2 level was found to be significantly higher in patients than healthy controls (P=0.005). In 29% of patients, serum HER2 levels were higher than the cut-off value. HER2 serum level was not associated with tumor stage at diagnosis.Conclusion: Elevation of HER2 in a high proportion of patients with epithelial ovarian cancer further strengthens the importance of this molecule in the pathogenesis of ovarian cancer.