Under the aegis of the GEEP (Groupement d'Etudes Epidémiologiques et Prophylactiques) a prospective multicentre study concerning bacterial endophthalmitis was carried out over a period of one year long with the contribution of 64 metropolitan ophthalmologic hospital departments. During this survey 143 cases of post surgical endophthalmitis were recorded: 111 of them were secondary to elective surgery, 32 developed after a perforating eye injury. Twenty-four cases of endophthalmitis developed in the absence of surgery were therefore called "medical" endophthalmitis. The frequency of endophthalmitis after elective surgery was 0.32%, and 2.8% after penetrating eye injury. Intraocular samples were obtained in 61.5% of the cases of post surgical endophthalmitis. 53 bacteria were isolated from 50 cases of endophthalmitis. The bacterial nature of the endophthalmitis was proved in 35% of these cases of post surgical endophthalmitis. Bacteria isolated from these cases of post surgical endophthalmitis were gram positive in 86.7%, and gram negative in 13.3% of cases. 20 bacteria were isolated from pseudophakic eyes: 10 of them were Staphylococcus epidermidis. The visual prognosis of endophthalmitis depends on the strain: visual acuity was more than 1/10 in 68% of cases of Staphylococcus endophthalmitis infection, but in only in 7% of cases of Streptococcus endophthalmitis infection. Intraocular injections of antibiotics both in the anterior chamber and in the vitreous, and vitrectomy increased the quality of the visual result. Three months after post surgical endophthalmitis, 35% of those eyes who received systemic and periocular antibiotic therapy, combined with intraocular antibiotics, with or without vitrectomy, recovered a visual acuity of 4/10 or more, instead of only 18% in the group without any intraocular therapy.