Objective To study the characteristics of optic al coherence tomography (OCT) in idiopathic macular epiretinal membranes (IMEM) and the relationship between the thickness of fovea and the vision of affected eyes. Methods Total of 67 cases (73 eyes) with clinica l diagnosis of IMEM by direct, indirect ophthalmoscopy, three mirror contact len s, fundus color photography or fundus fluorescein angiography(FFA）were examined with OCT. Results Epiretinal membranes(ERMs) with macular edema were found in 32 eyes, proliferative ERMs in 20 eyes, ERMs with macular pseudoholes in 14 eyes and ERMs with laminar macular holes in 7 eyes. Based on OCT, the ERMs were clearly and partially seperated from the retina (27 eyes, 38.36%), the retinal thickness of the fovea was the thickest in proliferative ERMs and the thinnest in ERMs with laminar macular holes. The statistical an alysis showed there was a negative correlation between the thickness of fovea an d visual acuity (r=－0.454, P= 0.000 ). Conclusion There were four types of image of OCT in IMEM: ERMs with macularedema, proliferative ERMs, ERMs with macular pseudohole and ERMs with laminar macular hole；and the thicker the fovea under the OCT, the poorer th e visual acnity in the affected eyes with ERMs. (Chin J Ocul Fundus Dis, 2001,17:115-118)