We describe two patients with autoimmune optic neuritis. The initial symptom was severe loss of vision without clinical signs or symptoms of systemic autoimmune disease. The patients had recurrent attacks of optic neuritis in both eyes, causing permanent visual impairment despite conventional doses of corticosteroid. The only laboratory sign of autoimmune disease was a positive antinuclear antibody (ANA). These patients must be differentiated from cases with idiopathic optic neuritis or multiple sclerosis. Early diagnosis and high-dose corticosteroid therapy may be necessary, and may be successful in restoring visual function. Continued therapy with cytotoxic agents may be required.