The purpose of this study was to evaluate the prognostic significance of serum human epididymis protein 4 (HE4) level in patients with epithelial ovarian cancer.A total of 78 women diagnosed with a pelvic mass and operated on in our institute comprised our cohort. Forty-five of these were diagnosed with epithelial ovarian cancer and treated with debulking surgery, followed by taxane and platinum-based chemotherapy as clinically indicated. Preoperatively obtained serum samples were analyzed for levels of HE4 and CA125.The elevated serum HE4 level was related to advanced stage and serous type of cancer. The median duration of the follow-up was 35.1 months. In advanced stage, the median progression-free survival (PFS) of patients with elevated serum HE4 levels was 20.1 months (95% CI, 15.7-24.6 months), whereas that of patients with normal serum HE4 level was 24.2 months (95% CI, 13.9-34.6 months) (p=0.029). Independent predictors for PFS in patients with advanced stage EOC included serum HE4 level (hazard ratio 2.24; 95% CI, 1.14 to 6.84; p=0.048).Our results demonstrated that an elevated serum HE4 level was related to the advanced stage of epithelial ovarian cancer. An elevated serum level of HE4 is a poor prognostic factor for PFS in patients with epithelial ovarian cancer who were treated with debulking surgery and adjuvant taxane and platinum-based chemotherapy. The serum HE4 level is a promising indicator for the progression of cancer as well as a biomarker for the detection of epithelial ovarian cancer.