Mechanisms accounting for the development of proliferative vitreoretinopathy (PVR) in patients with rhegmatogenous retinal detachment remain poorly understood. In a previous study, we found the presence of various growth factors in preretinal membranes that were surgically removed from patients with PVR. The present immunohistological study was undertaken in intravitreal and subretinal fluid cells from patients suffering from PVR in various stages of development, in order to seek the presence of 4 growth-promoting factors for retinal pigment epithelial cells: acidic fibroblast growth factor (FGF), epidermal growth factor (EGF), insulin-like growth factor type I (IGF-I) and transforming growth factor-beta (TGF-β). Results were quite similar in vitreous and subretinal fluid. Acidic FGF was found in all vitreous and subretinal specimens, in 30-100% of the examined cells. Immunoreactivity for EGF could be found in 53% of intravitreal cells and 69% of subretinal fluid cells. Positive cells were seen in all vitreous specimens and in all but 1 of the subretinal fluid specimens. IGF-I-containing cells were present in 13 of 15 vitreous specimens and in 18 of 20 subretinal fluid samples (mean percentages of reactivity in positive specimens 70% and 78%, respectively). In contrast, TGF-β1 reactivity was found in only 8 of 15 vitreous specimens and in 11 of 20 subretinal samples. Mean percentages of reactive cells were 30% and 50%, respectively. These results suggest that several growth factors could be involved in the proliferation and migration of retinal pigment epithelial cells during the course of PVR. Their respective role and whether they act solely or synergistically are, however, some of the numerous questions that remain to be investigated.