Compare membrane dissections and en bloc membranectomy in vitrectomy of proliferative diabetic retinopathy. Retrospective comparative (non-randomized) interventional study. 296 eyes of 276 patients with fibrovascular proliferation in diabetic retinopathy performed by vitrectomy from 1996 approximately 2000 were analyzed. 201 eyes complicated with vitreous hemorrhages in different severity, 110 eye with traction retinal detachment. We used membrane dissection in 110 eyes and en bloc excision in 186 eyes. Follow up time required more than 4 months, for the silicone oil temponade eyes required 3 months after silicone oil removal. The iatrogenic holes, postoperative hemorrhages, rubeosis iridis and visual improvement were compared in the same intraocular temponade for membrane dissections and en bloc excision, as well as visual acuity > 0.1. There is no statistic significant difference in age, sex and type of fibrovascular proliferations for both groups. Membrane dissection techniques showed a lower incidence of iatrogenic breaks (35.5%) than that in en bloc membranectomy techniques, no significant difference in postoperative vitreous hemorrhages and visual improvement for both techniques. Both techniques showed no difference to visual results and postoperative complications, but membrane dissection techniques can decrease the formation of iatrogenic breaks.