Intraocular non-Hodgkin lymphoma often masquerades a chronic uveitis, which does however not respond to local and/or systemic immunosuppressive treatment. The anterior segment signs are usually discrete, although a hypopion may appear during evolution. The vitreous is often markedly involved. The chorioretinal lesions are variable in aspect. Subretinal infiltrates or solid retinal pigment epithelial detachments are the most characteristic fundus signs of the disease. Other fundus signs may be present, such as retinal vascular occlusions, perivasculitis, macular oedema, optic disc oedema or ischaemic optic neuropathy. The diagnosis is based on histological or cytological examination of anterior chamber material in case of hypopion, or more frequently from vitrectomy specimens or from direct biopsy of suspected fundus lesions. Polymerase chain reaction and flow cytometry can be extremely helpful in the diagnosis of intraocular lymphoma when the cytology is not conclusive.