A patient with paranasal sinus lymphoma (recognized retrospectively) developed unilateral, acute, self-limited optic neuritis during the course of chronic lymphocytic meningitis with elevated intracranial pressure and headache. Meningeal symptoms were adequately controlled with analgesics alone for 14 months and corticosteroids alone for a subsequent 11 months without evidence of development of other involvement of organs outside the central nervous system (CNS). Eventually, the visual alteration from optic neuritis prompted a repeat evaluation, which disclosed lymphoma in bone marrow. The subject of paraneoplastic optic neuritis is reviewed.