The authors report four cases of chronic endophthalmitis following extracapsular cataract extraction with intraocular lens implantation in the posterior chamber. The first attack of intraocular inflammation occurred in the form of recurrent iridocyclitis two to six months after surgery. The first attack usually responded well to local corticosteroids. After many relapses of inflammation, increasingly resistant to medical treatment, a severe attack occurred leading to the decision to treat such endophthalmitis surgically: endocular fluid aspiration, vitrectomy, intraocular injection of antibiotics combined with systemic antibiotics and corticosteroids. It may be very difficult to prove the infectious origin of torpid endophthalmitis. Growing bacteria from endocular fluid aspirates is much more difficult than in acute endophthalmitis. No organisms were found in this series by this method, despite the fact that fluid aspiration was often performed many times in these 4 cases. A bacterium was identified in 3 cases, twice on the implant itself and once after culture of an iridectomy specimen. Intraocular antibiotic injections resulted in the complete recovery of one patient. Following failure of standard treatment, intraocular lens explantation resulted in the disappearance of infectious inflammatory signs in 3 cases. The treatment of chronic endophthalmitis is governed by the same rules as acute endophthalmitis but is not always as successful. Intraocular lens removal is often the only solution and confirms the pathogenic hypothesis that slime production by organisms, their adherence to the intraocular lens and their quiescent state make them less vulnerable to antibiotics and host defences.