A three-year retrospective study of 36 cases of infectious endophthalmitis seen at a large referral eye center between 1977 and 1980 was conducted. The criterion for infectious endophthalmitis was the culture of microorganisms from aqueous or vitreous on at least two media. The most frequent pathogen was Staphylococcus epidermis; it was isolated from 18 (50%) of the cases. In cases of infectious endophthalmitis following recent cataract extraction, S. epidermidis was isolated from 10 to 17 eyes (58.8%). Complete loss of visual function occurred in 16 of the 36 eyes (44.4%); a visual acuity of 20/400 or better as recorded in 15 eyes (41.6%) and 20/100 or better in eight (22.2%). Fifty percent of the cases were treated with vitrectomy and intraocular antibiotics. Poor visual outcome was associated with gram-negative organisms or delay of vitrectomy more than 24 hours after the initial diagnosis. In cases of postoperative S. epidermidis endophthalmitis, the most favorable visual outcomes were associated with use of intraocular antibiotics and vitrectomy; 80% of cases so treated had a final visual acuity of 20/400 or better and 60% had a visual acuity of 20/100 or better.