Aim To investigate whether the lipid peroxidation of endothelial cells had any effect on the production of growth factors by them.Methods The bovine aortic endothelial cells were isolated and cultured using an enzyme-dispersal method, and the media conditioned by endothelial cells with lipid peroxidation induced by cumene hydroperoxide were collected. Then the endothelial cell-conditioned media (ECCM ) were treated by heparin-binding sepharose, and the mitogenic activity of ECCM for swiss 3T3 cells were determined by incorporation of 3H-thymidine into DNA of the cells. The concentration of endothelin in the media of endothelial cells were analysed by radioimmunoassay.Results Cumene hydroperoxide induced storage oflipid peroxide in cultured endothelial cells, and there was an obvious increase in the incorporation of 3H-thymidine into DNA in Swiss 3T3 cells treated with ECCM compared with the control. However, the mito-genic activity of ECCM for Swiss 3T3 cells were in non heparin-binding parts. Then the concentration of en-dothelin in the media of endothelial cells were treated by cumene hydroperoxide were increased obviously compared with the control.Conclusion It seems reasonable to believe that lipidperoxidation of endothelial cells induced by cumene hy-droperoxide leads to an increased synthesis and secre-tion of growth factors, and the mitogenic activities were due to non heparin-binding parts like as endothe-lin.