The expression of p53 protein and overexpression of c-erbB-2 oncoprotein was examined immunohistochemically and compared on frozen tissue sections and cyst fluid cells in patients with epithelial malignant and benign ovarian neoplasms. p53 was detected in 52.6% of carcinomas and c- erbB-2 expression was identified in 47.3% of cases. The relationship between p53 and c-erbB-2 overexpression in tissue sections and detached cyst fluid cells was evident. Moreover, a significant association between the presence of p53 and overexpression of c-erbB-2 proteins in tumor tissue sections and loose cyst fluid cells in individual patients was demonstrated. In tissue sections and loose cyst fluid cells of benign ovarian tumors no overexpression of p53 and c-erbB-2 proteins was found.