A 41-year-old woman presented with a unilateral optic neuropathy that progressed to no light perception 7 weeks later. The patient was hospitalized for progressive dyspnea; respiratory failure ensued and the patient died 10 days after admission. Antemortem pulmonary biopsies and the results of necropsy revealed lymphomatoid granulomatosis with extensive involvement of the lungs and left optic nerve. This is the first case report of lymphomatoid granulomatosis presenting as a unilateral optic neuropathy.