Human epididymis factor 4 (HE4) is a novel biomarker for ovarian cancer. The aim of this study is to assess the usefulness and efficacy of HE4, in comparison with CA-125 in the differential diagnosis of malignant and benign gynecological diseases in women with adnexal masses. Materials and methods: 85 patients diagnosed with adnexal mass who were operated at a tertiary referral center between the years of October 2012 and February 2013 were included in the study. Demographic data, physical examination, results of the laboratory tests, imaging, and pathology were recorded from all subjects. Blood samples were collected before surgery for the evaluation of HE4 and CA-125 levels. Patients were divided into 4 groups according to their histopathologic diagnosis: benign (n:58), malignant (n:17), borderline (n:5) and metastatic (n:5) and serum CA-125 and HE4 levels were compared considering menopausal status. Results: Using 35 U/mL as the cut-off value, CA-125 had a sensitivity of 82.4%, spesificity of 67.2%, a negative predictive value of 92.9%, and a positive predictive value of 42.4%. For the same sensitivity level, specificity was 87.9%, negative predictive value was 94.4%, and the positive predictive value was 66.7% for HE4. Receiver operator characteristic (ROC) area under the curve was higher in both the premenopausal and postmenopausal group for the HE4 curve. Accordingly, sensitivity at set specificity of 90% was 82.4%, and 70.6% for 95% of specificity and 41.1% for 98% for HE4. Same sensitivity values for CA-125 were 47.1%, 35.3% and 23.5%, respectively. Conclusion: According to our study, especially in the premenopausal period, HE4 shows higher sensitivity and specificity values than CA-125.