Objective To observe the therapeutic effect of poly tetrahydrofurfuryl co-lactic acid(copolymer C4) as the biodegradable vitreous substitutes on rhegmatogenous retinal detachment.Methods Vitreoretinal surgery with copolymer C4 tamponades was performed on 32 pigmented rabbits (64eyes) with rhegmatogenous retinal detachment. The rate of reattached retina and the post operative cornplications were observed.Results Three months after the operation, reattached retina was found in 96. 4%, glaucoma in 5.5%, cataract in 10.9%, and copolymer emulsion in 10.2% of all the eyes.Conclusion copolymer C4 may withstand the retinal tear effectively for 3 months, and can be a valuable vitreous substitutes. (Chin J Ocul Fundus Dis，2004，20：27-28)