Purpose. - To assess the visual and anatomic outcomes of pars plana vitrectomy for diabetic macular edema associated with an epiretinal membrane. Patients and methods. - In this retrospective study, vitrectomy with epiretinal membrane peeling was performed in 36 eyes of 28 diabetic patients diagnosed with diabetic macular edema associated with an epiretinal membrane. Fifteen eyes, in which preoperative central macular thickness was over 500 p m, underwent intravitreal triamcinolone acetonide injection during surgery. The main outcome measures were changes in best corrected visual acuity and central macular thickness, measured 3 and 6 months after surgery by optical coherence tomography (OCT). Results. - A significant gain in visual acuity was observed 3 months after surgery (-0.15 +/- 0.21 Log MAR, P < 0.01), and this gain remained stable at 6 months (-0.15 +/- 0.17 Log MAR, P < 0.01). Significant decreases in central macular thickness were observed both 3 months (-157 +/- 136 mu m, P < 0.01) and 6 months after vitrectomy (-128 +/- 195 mu m, P 0.01). Intraoperative intravitreal triamcinolone acetonide injection, the presence of a posterior vitreous detachment in the operated eye at the time of surgery or that of macular edema in the fellow eye, did not affect postoperative visual acuity or central macular thickness. Conclusion. - Pars plana vitrectomy is effective in improving visual acuity and reducing macular thickness in the mid term in eyes with diabetic macular edema associated with an epiretinal membrane. (C) 2013 Elsevier Masson SAS. All rights reserved.