In this study, expression of the c-erbB-2 gene in tumors and healthy tissue of patients with ovarian cancer was investigated. Serum c-erbB-2 protein levels were also determined. Elevated serum values were observed in 45% of patients. c-erbB-2 protein levels in the tumors were significantly higher than in healthy tissue. Overexpression of the protein was observed in 60% of patients. However, no association was found between the clinical variables and tumor c-erbB-2 expression. This is the first study in the literature investigating the c-erbB-2 oncoprotein levels in the normal and tumor tissue. We conclude that the role of the c-erbB-2 gene in ovarian cancer warrants further studies.