We evaluated the effect of intraocular silicone oil as an internal tamponade on an animal model of proliferative vitreoretinopathy. Lensectomy and vitrectomy were performed on two groups of pigmented rabbits. Twenty-five rabbit eyes then had 1,000 centistokes' viscosity silicone oil injected into the vitreous cavity; 20 control eyes received balanced salt solution. Fourteen days later, each eye was injected with homologous fibroblasts (ten eyes with 100,000 cells, 25 eyes with 250,000 cells, and ten eyes with 750,000 cells). All membranes that developed after the cell injections in both experimental and control eyes produced traction retinal detachment. The character of the membranes formed and the timing of the traction retinal detachment were the same for both groups. In an active phase of experimental proliferation, the internal tamponade of silicone oil is insufficient to keep the retina in place.