We studied the inhibitory effect of triamcinolone acetonide on experimental intraocular proliferation. Autotransplantation of fibroblasts from rabbit rump skin into the vitreous cavity resulted in intravitreal strand formation and traction retinal detachment in 36 of 43 eyes (84%) over a period of three months. A single intravitreal injection of 1 mg of triamcinolone acetonide inhibited fibroblast growth and significantly reduced the number of retinal detachments in 15 of 44 eyes (34%). Retinal neovascularization caused by fibrous strands coming into contact with vacularized retina was also reduced by triamcinolone acetonide (31 of 43 control eyes [72%] vs eight of 44 treated eyes [18%]). Intravitreal corticosteroid therapy may be an important adjunct to the therapy of perforating injuries and massive periretinal proliferation.