Anaerobic bacterial endophthalmitis was studied in rabbits following intravitreal injection of live Fusobacterium necrophorum. Clinical response, bacterial recovery, and histopathology were studied. An inoculum of approximately 50 organisms produced endophthalmitis in 59% of injected eyes, while 1000 or more organisms produced endophthalmitis in 100% of injected eyes. The course and severity of disease seemed to be independent of the concentration of bacteria above a minimal inoculum size. Affected eyes showed progressive endophthalmitis. Histopathologic changes corresponded to the clinical gradation of endophthalmitis, including progressive retinal necrosis.