AIM:To study the expression of vessel endothelial transforming growth factor-β(TGF-β) in choroidal neovascularization(CNV) induced by argon laser in RWH rats.METHODS:Three groups of 21 RWH rats were photocoagulated by argon laser in single eye.1 week,2 weeks,3 weeks after photocoagulation,the expression of TGF-β,and factorⅧ related antigen(FⅧR:Ag) was observed by immunohistochemical method.RESULTS:The result of FⅧR:Ag immunohistochemistry showed that CNV initially formed 1 week after photocoagulation and reached the peak till 3rd week.TGF-β expression was observed in the ganglion cells,inner nuclear layer,retinal pigment epithelial cells,the vascular endothelial cells of retina and choroid in normal rats.Besides the above part,TGF-β expressed positively in the outer nuclear layer and choroid after retinal photocoagulation.1 week to 3 weeks after photocoagulation,the positive stained density of FⅧR:Ag and TGF-β in faculous region gradually increased(P<0.05).The expression of FⅧR:Ag was positively correlated with that of TGF-β(r=0.83,P<0.05).CONCLUSION:CNV is positive correlated with the expression of TGF-β.The increased expression TGF-β may contribute to the main reason for the formation and development of CNV.