C-erbB-2(HER-2 / neu) proto-oncogene is mainly expressed in epithelial tissue and activated due to its amplification. Amplification of the C-erbB-2 proto-oncogene has been associated with poor prognosis in human ovarian cancer. Our study was to examine whether amplification is more frequently observed in ovarian cancer, or it is associated with poor prognosis of human ovarian cancer in China. The DNA of ovarian cancers was extracted and consequently digested with restriction endonuclease EcoRI, electrophoresed in 0.8% agarose gels and blotted onto nitrocellulose filter with Southern transfering method. It was then hybridized with a 32P-labelled C-erbB-2 probe and subsequently underwent autoradiography. The result has shown that the C-erbB-2(HER-2 / neu) gene was amplified in 8 of 26 human ovarian cancers (30.8%). The clinical data showed that all of the 8 cases with the amplified C-erbB-2 were in their advanced stage (III-IV). Five of the patients died from 2 to 4 months after operation. These data sugge C-erbB-2 (HER-2 / neu) proto-oncogene is mainly expressed in epithelial tissue and activated due to its amplification. Amplification of the C-erbB-2 proto-oncogene has been associated with poor prognosis in human ovarian cancer. Our study was to examine whether amplification is more frequently observed in ovarian cancer, or it is associated with poor prognosis of human ovarian cancer in China. The DNA of ovarian cancers was extracted and hereby digested with restriction endonuclease EcoRI, electrophoresed in 0.8% agarose gels and was blotted onto nitrocellulose filter with Southern transfering method. It was then hybridized with a 32P-labeled C-erbB-2 probe and succeeded underwent autoradiography. The result has shown that the C-erbB-2 (HER-2 / neu) gene was The clinical data showed that all of the 8 cases with the amplified C-erbB-2 were in their advanced stage (III-IV). Five of the patients died from 2 to 4 months after operatio n. These data sugge