Endogenous endophthalmitis is a severe and potentially blinding complication of hematogenous spread of microorganisms. Predisposing factors are intravenous drug abuse, immunosuppression, and prolonged intensive care. Intraocular material needs to be cultured or subjected to PCR to detect the causative microorganisms. In contrast to PCR, culture has the advantage of providing additional information about the resistance of the microorganism. Fungi and bacteria cause endogenous endophthalmitis with the same frequency. Treatment consists in a combination of local and systemic antibiotics or antimycotics, systemic and local corticosteroids, and vitrectomy. The prognosis depends mainly on the initial visual acuity and the pathogen concerned.