Objective To investigate the effect of exogenous Rb gene on the cell cycle of vitreous retinoblastoma (RB) transplantation tumor in nude mouse. Methods Based on establishing vitreous RB transplantation tumor in nude mouse,constructing retrovirus vector of Rb gene PBabe-Rb and transfecing it into the RB transplantation model by liposome Dosper,the change of cell cycle of the RB transplantation tumor by flow cytometry(FCM)was analysed． Results FCM showed that the cells of G1phase of the treated eyes were obviously more than the control eyes with the value of DNA index(DI)and S phase fraction(SPF) decreased by the Rb gene expression. Conclusion The exogenous PBabe-Rb gene can partially suppress the progress of the cell cycle of RB transplantation tumor in vivo. (Chin J Ocul Fundus Dis，2000，16：1-70)