The intraocular distribution of fosfomycin was studied in 32 patients undergoing cataract surgery and in 8 rabbits after experimental infection of one eye by Staphylococcus aureus. Concentrations found 1 to 6 hours after termination of a 4 g fosfomycin infusion ranged from 14 to 18.8 mg/l in the aqueous humor and 8 to 12.5 mg/l in the vitreous body. These levels are higher than the MICs for 80 to 90% of the bacteria responsible for endophthalmitis. In each rabbit, the fosfomycin concentration in the infected eye as compared to the healthy eye was increased 2.5 to 5--fold for the aqueous humor and 4.9 to 19.2--fold for the vitreous body. Fosfomycin, in association with a third generation cephalosporin (ceftriaxone) or one of the new quinolones (pefloxacin) can be recommended for the prevention or early treatment of endophthalmitis.