Bacterial endophthalmitis is a postoperative complication of intraocular lens implantation. A review of 30 cases showed that 77% occurred within seven days of initial cataract surgery and that all cases occurred within 32 days. Common presenting symptoms and signs included pain localized to the involved eye, decreased visual acuity, conjunctival injection, anterior chamber inflammation, hypopyon, and absent or poor red reflex. Diagnosis of an infectious etiology was made by aqueous and vitreous sampling for gram stain and culture. The commonest bacterial agents were coagulase-negative staphylococci and Staphylococcus aureus, but a wide variety of gram-negative and -positive organisms were also isolated. On the basis of this series and review of the literature, optimal treatment includes prompt diagnosis by culture and gram stain of vitreous fluid, frequent application of topical antibiotics, and administration of intraocular antibiotics. Intravenous antibiotics and vitrectomy may improve the visual outcome. Removal of the intraocular lens is unnecessary for bacteriologic cure and is not associated with improved visual outcome.