Purpose: was to assess the results of vitrectomy with and without internal limiting membrane (ILM) peeling on retinal function and anatomy in patients with diabetic macular edema (DME). Methods: Pars plana vitrectomy (PPV) was done in 40 eyes of 40 patients with DME (15 male, 25 female). Patients were enrolled randomly into two different groups. Group A- comprised (20) eyes who underwent vitrectomy without ILM peeling. Group B- comprised (20) eyes who underwent vitrectomy with ILM peeling. For each patient, visual acuity (VA) examination (in decimal charts), assessment of central macular thickness (CMT) with optical coherence tomography (OCT) and multifocal eletroretinogram (MF-ERG) were done before and 3 months post vitrectomy. Results: Postoperative mean VA increased significantly (from 0.17 to 0.27 in group A and from 0.21 to 0.38 in group B). Mean CMT decreased significantly after surgery (from 493 μm to 315 μm in group A and from 502 μm to 299 μm in group B). Mean P1 wave amplitude (nV/ deg2) in the macular area increased after surgery (from 32.15 to 41.10 in group A and from 35.5 to 40.8 in group B). Mean P1 wave latency (millisecond) in the macular area decreased after surgery (from 50.30 to 36.40 in group A and from 49.5 to 39.2 in group B).Conclusion: Vitrectomy with and without ILM peeling improve VA and macular edema in diabetic patients moreover an increase of amplitude and reduction of the latency of the macular mf-ERGs indicated an improvement of the macular visual function.