Biomorphometric studies using optical coherence tomography (OCT) in patients with epiretinal membranes reveal a highly reflective membrane, a significant foveal thickening, loss of the foveal depression, and the presence of intraretinal cysts. Epiretinal membranes are more frequently totally adherent than separated with focal points of adherence. Visual acuity correlates with foveal thickness prior to and 6 months after vitrectomy and surgical removal of epiretinal membranes. Foveal thickening regresses postoperatively, but normal values are seldom reached. Marked foveal thickening, nonexistent foveal depression, and extensive cyst formation are supposed to correlate with a rather poor visual outcome. OCT plays a pivotal role in the differential diagnosis of pseudomacular hole in epiretinal membranes and of full-thickness macular hole. In addition to biomicroscopy and fluorescein angiography, OCT images provide valuable information for a structural assessment of the macula, especially in evaluating the postoperative course of macular surgery.