Diagnostic anterior chamber and vitreous aspiration confirmed an infectious etiology in 78 of 140 eyes (56%) with suspected endophthalmitis. In 27 eyes the vitreous aspirate was positive, while the anterior chamber aspirate was negative. Intraocular antibiotics were used in 88 eyes including 50 which underwent therapeutic vitrectomy. Vision of 20/20 to 20/400 was achieved in 57% of recently operated, culture-positive eyes treated with intraocular antibiotics, and in 59% of those treated with combined vitrectomy and intraocular antibiotics.