The histological features of vitrectomy entry sites were studied in a group of monkeys following pars plana vitrectomy for experimental posterior penetrating injury. The extent of fibrocellular proliferation and vitreo-retinal complications arising from the vitrectomy wounds were compared to the proliferation from a much larger penetrating trauma site after complete and partial (core) vitrectomies. Although scarring and complications were more severe following core vitrectomy, there was little difference on histological examination between fibrocellular proliferations from the vitrectomy entry sites and from the penetrating wound.