This report reviews current knowledge of the ultrastructural features of the vitreoretinal juncture in its normal state, in eyes with posterior vitreous detachment (PVD), and in eyes with epiretinal membranes (ERM's) and then presents new concepts concerning the interrelationship of ERM's and the vitreous. Results show no vitreous residues on retinal surface following uncomplicated rhegmatogenous (senescent) PVD. In eyes that develop ERM's before vitreous detachment, however, a layer of vitreous may be entrapped beneath the ERM and on adjacent membrane-free retina when PVD ocurs. ERM's may be a cause as well as an effect of PVD.