Progressive fibrovascular proliferation may occur despite appropriate panretinal photocoagulation in diabetic patients. Fibrovascular proliferation may lead to persistent or recurrent vitreous hemorrhage, macular traction, or traction macular detachment, and becomes a major indication for vitrectomy.1 During the past 25 years, anatomical and visual results of vitrectomy for severe proliferative diabetic retinopathy have improved as a result of improved understanding of the pathoanatomy and improvements in surgical instrumentation.2-5 Although anatomical success is high after complete vitrectomy, recurrent epiretinal membrane may cause macular thickening, cysts formation, preventing good functional outcome.6 An epiretinal membrane (ERM) is a non-vascular cellular membrane that may cause symptomatic visual disturbances due to retinal wrinkling and distortion.7 These epiretinal membranes have been found to be composed of fibroblasts, glial cells, macrophages, myofiboblasts, nad retinal pigment epithelial cells.8-9 Studies have suggested removal of internal limiting membrane (ILM) may decrease the likelihood of post-operative ERM formation in cases of diabetic macular edema and idiopathic ERM. It is postulated that removal of the ILM removes the scaffold upon which myofibroblasts would proliferate.10 Efficacy of vitrectomy including removal of ILM was mostly described as facilitating resolution of diffuse diabetic macular edema11 and improvement of visual acuity or in macular hole surgery in diabetic patients.12However, it is unknown if removal of ILM during vitreoretinal surgery in diabetic patients with active fibrovascular proliferation is useful in preventing postoperative ERM formation. The purpose of this study is to compare the postoperative epiretinal membrane (ERM) formation and visual outcome in diabetic patients with active fibrovascular proliferation who underwent vitrectomy with or without ILM peeling.