A retrospective study of 40 cases of postoperative endophthalmitis was conducted between July 1979 and May 1981. Treatment consisted of topical, periocular, and systemic antibiotics, as well as the use of intraocular antibiotic injection in all cases. In addition, 22 cases had a diagnostic and therapeutic vitrectomy. The cases selected for vitrectomy included cases with worse presenting visual acuity, higher percentage of positive culture results, and more virulent organisms. Because of a poor clinical response to initial therapy, 13 cases had repeat intraocular cultures performed between 24 and 72 hours at the time of repeat intraocular antibiotic injection. All 13 repeat intraocular cultures were negative. Complications of the treatment included four retinal detachments (three in the vitrectomy group). In the culture-positive cases, a final visual acuity of 20/400 or better was achieved in 13 of 29 cases (45%), and complete loss of vision (NLP) resulted in 10 of the 29 cases (34%).