c-erbB-2 oncogene is a gene that encodes a growth factor receptor-like molecule with tyrosine kinase activity and has a structure similar to that of the epidermal growth factor receptor. Overexpression of the c-erbB-2 oncoprotein is detected in human adenocarcinoma of the breast, cervix, and salivary gland, in all of which the association between overexpression of the c-erbB-2 and poor prognosis of the disease has been reported. The role of c-erbB-2 oncoprotein in the tumorigenesis of the human ovary has been poorly understood and remains controversial. In order to explore the relationship between c-erbB-2 oncoprotein status and ovarian carcinoma, tissue from 32 patients, each of whom had invasive ovarian carcinoma prior to treatment, 10 patients with benign cyst and 10 control case who underwent hysterectomy due to gynecological disease at Yonsei University Colloge of Medicine were analyzed. We measured c-erbB-2 oncoprotein with an enzyme-linked immunosorbent assay(ELISA) which was a sandwich type. Patients with invasive ovarian cancer were found to have significantly higher median c-erbB-2 oncoprotein expression than patients with either benign ovarian cyst(P<0.05) or control group(P<0.05), respectively. However there was no significant difference in c-erbB-2 oncoprotein status between benign cyst and control group. verexpression of c-erbB-2 oncoprotein was found in 7 of 32(21.9%) epithelial ovarian cancer. In invasive epithelial cancer, no significant difference in c-erbB-2 oncoprotein levels was noted when stratified according to age, menopausal status, histological cell type, tumor size or surgical stage. Our results were consistent with the concept that c-erbB-2 oncoprotein may play an important role in malignant and tumorigenesis in epithelial ovarian cancer.