Despite many advances in microsurgery, asepsis, antibiotics and intraocular lenses, postoperative endophthalmitis continues to be responsible for the loss of many eyes. In a series of 153 cases of endophthalmitis with a positive culture, 115 occurred after ophthalmic surgery. Eyes appear to be more vulnerable to this complication after extracapsular lens extraction in particular. The analysis of the patients operated for cataract in our own department shows that the incidence of endophthalmitis is 3 times higher in the extracapsular group with lens implantation than in the group of intracapsular lens extraction without lens implantation. Quick diagnosis and prompt action are essential to successful treatment. The treatment consists of vitrectomy and has the following three purposes: (1) provision of a good specimen for direct bacteriological examination and culture; (2) removal of toxins and cells, and (3) creation of space for the injection of an antibiotic. The authors found highly divergent prognoses and bacteriological patterns for endophthalmitis following vitrectomy, bleb surgery and cataract. Similar bacteriological agents do not give rise to the same prognosis after different operations. The post-lens implantation group (88 cases) permitted a distinction to be made between intracapsular and extracapsular surgery. A statistically significantly higher percentage of infection by low-virulence organisms (e.g. Staphylococcus epidermidis) was seen after extracapsular surgery: 60% compared to 30%. The analysis shows that this difference in bacteriological spectrum is the sole explanation for the better functional results following extracapsular surgery.