Abstract: PURDOSE:To evaluate whether endothelin(ET) can be synthesized by and released from human hepatoma cells.and whether ET Stimuates Proliferation of the tumor cells.METHODS:By using a specific ET-1 radioimmunoassay，ET-1 was detected in the conditioned media from HCC9204 cells and SMMC7721 cells. ET-1 (10^-10~10^-7mol/L) was added to cultures of HCC9204 cells with or without epide-mal growth factor (EGF) and Proliferation rates of the cells -were measured with(³H)-thymidine incorporation and liquid scintillation techniques.RESULTS:ET-1 was released from both HCC9204 and SMMC7721 cells as a function of time，reaching a plateau after 24h.CONCLUSION:Human hepatoma cells may produce and Secrete ET.ET-1 alone didn't stimulate DNA synthesis in the cells.But ET-1 Potentiated markedly DNA Synthesis stimulated by EGF.