In this work 50 cases of ovarian tumors were studiedHistopathologicallyImmunohistochemically for C-erbB-2 expressionFlow cytometric study for DNA ploidy and S-phase fractionFrom our study we conclude the following:1- There is extensive expression of C-erbB-2 in epithelial ovarian tumors and it is overexpressed in ovarian carcinoma.2- The expression of C-erbB-2 in borderline tumors tend to be like that of benign tumors, so these lesions are in fact benign and better classified as proliferative except in the minority they turn frankly malignant.3- No significant correlation between of C-erbB-2 expression and the clinicopathological parameters including histologic type, tumor grade and tumor stage.4- C-erbB-2 expression is of importance in patients with ovarian carcinoma who are under therapeutic planes.5- No significant relation between C-erbB-2 expression and flowcytometric measurementa concerning DNA ploidy, S-phase fraction level and DNA index in ovarian tumors.6- C-erbB-2 expression in germ cell tumors and sexcord-stromal tumors is indefinite and has no indication7- Flowcytometric measurements concerning DNA ploidy, S-phase fraction level and DNA index in ovarian tumors are reflective of the biological state of the cell.8- A fairly good correlation between DNA ploidy, S-phase fration and grade stage of ovarian carcinoma and so it is of value in predicting the prognosis.9- A fairly good correlation between DNA ploidy and S-phase fraction.