Objectives: The aim of this study was to assess the sensitivity and specificity of HE4 in detecting and differentiating between types I and II epithelial ovarian cancer (EOC) in comparison with CA125. Material and methods: We measured HE4 and CA125 serum concentrations in 206 samples taken from patients operated in Gynecologic Oncology Department due to ovarian tumors. Ovarian cancer was confirmed in 89 cases divided into type I and type II. 52 healthy patients without any gynecological disease formed the control group. The sensitivity and specificity for type I and type II EOC detection and differentiating between both types was evaluated for HE4 and CA125. Results: The HE4 and CA125 serum concentrations were significantly higher in type II than in type I EOC (p=0.008696, p=0.000243 respectively).The HE4 and CA125 sensitivity for type I and benign tumors differentiation was 63.16% for both of them and specificity was 87.29% vs 67.89% respectively. For CA125 these differences did not reach statistical significance. The HE4 sensitivity and specificity for type II and benign tumors differentiation were 87.14% and 96.61%, respectively, and for CA125 these values were 82.86% and 94.07%, respectively. Conclusions: Pretreatment analysis of HE4 serum concentration is superior to CA125 in differential diagnosis of ovarian cancer subtypes (I and II). HE4 is superior to CA125 in detecting ovarian cancer type II. Neither HE4 nor CA125 is an effective diagnostic tool for type I ovarian cancer detection. A new highly specific and highly sensitive tumor marker for type I EOC is needed.