AIM:To evaluate the effects ofpars plana vitrectomy(PPV) combined with internal limiting membrane peeling for the treatment of macular edema secondary to retinal vein occlusion (RVO).METHODS:Twelve cases of visual loss due to macular edema caused by central RVO or branch RVO underwentPPV combined with internal limiting membrane peeling. Best-corrected visual acuity (BCVA) and central foveal thickness by optical coherence tomography(OCT) were measured pre- and postoperatively then compared to assess the outcome of surgery.RESULTS:In all cases retinalthickeness diminished within 2 months of surgery. Visual acuity improved in all of the central RVO cases and 4 out of 8 branch RVO cases. The decrease in macular thickness was statistically significant (mean postoperative macular thickness 361±61.1μm versus mean preoperative macular thickness 563.9±90.0μm, P=0.001, t-test). The improvement in BCVA was not statistically significant (mean preoperative BCVA in LogMAR 1.23±0.29 versus mean postoperative BCVA in LogMAR 1.06±0.49, P=0.09, t-test).CONCLUSION: In eyes with macular edema secondary to RVO,PPV combined with internal limiting membrane peeling can resolve macular edema, but the improvement in BCVA was not statistically significant in this study.