A series of 500 consecutive pars plana vitrectomies was evaluated with regard to retinal complications. If the retina is attached preoperatively the risk of retinal complications is only 2.0%; however, in cases with preoperative detachment it rises to 9.2%. When membrane peeling is performed the risk rises by a further 7.3%. These statistics support the view that early vitrectomy is today a safe operation in cases with a simple initial anatomical situation. In contrast, late vitrectomy in cases where the initial anatomical situation is complex and membrane-peeling has to be performed is necessarily associated with a higher rate of complications.