• Several studies have focused on retinal pigment epithelial (RPE) cell proliferation as an important event in proliferative vitreoretinopathy (PVR). Little attention has been given to the question of how RPE cells gain access to the vitreous cavity where proliferation occurs. We have recently demonstrated that the serum components fibronectin and platelet-derived growth factor stimulate and direct RPE migration in vitro. In this study, we used this same in vitro technique to examine vitreous aspirates from 13 eyes with PVR, five eyes with macular puckers, and three eyes with uncomplicated retinal detachments for their ability to stimulate RPE migration. We found that aspirates from eyes with PVR stimulated RPE migration to a much greater extent than aspirates from eyes with macular pucker and uncomplicated retinal detachments. The ability to stimulate RPE cell migration correlated with high levels (mean ± SEM, 178 ± 67 mg/L) of immunoreactive fibronectin.