INTRODUCTION: Epiretinal tissue proliferations occurring during the evolution of ischemic microangiopathies or preretinal diseases are tough to cause retinal detachment by traction mechanisms. Cellular migration/proliferations and finally contraction are tough to be the pathogenic element. Myofibroblasts are contractile cells having features intermediate between those of the fibroblasts and smooth muscle. We conducted a study to explore whether such cells are present in preretinal membranes. MATERIALS AND METHODS: 8 membranes, preelevated during vitrectomy for proliferative vitreoretinopathy or diabetic proliferative vitreoretinopathy, were analysed with immunostaining technique searching for alpha-actine smooth muscle, desmine, which are specific markers for myofibroblasts and TGF-beta1, that is considered as the mean factor promoting the transformation of fibroblasts into myofibroblasts. RESULTS: All the histological preparation showed abundant staining with antibody against alpha-actine smooth muscle, desmine and TGF-beta1. CONCLUSIONS: Myofibroblasts are one of the major cellular element of preretinal membranes. They are scattered throughout the membrane and seem to account for their contractile properties.