We describe a patient with Leber's hereditary optic neuropathy (LHON) who had a unilateral involvement and a gradual recovery of vision. A 50-year-old woman was referred to our clinic in December 2004 for the treatment of left optic neuritis. The visual acuity was 0.01 in her left eye and 1.5 in her right eye. The left eye had a central scotoma and a relative afferent pupillary defect. Ophthalmoscopy revealed a hyperaemic optic disc with indistinct margins in the left eye. Fluorescein angiography showed circumpapillary microangiopathy in both eyes and staining of the left optic disc. An nt 11778 mutation was identified and she was diagnosed with LHON. The central scotoma gradually improved, and the visual acuity had recovered to 0.3 in August 2007. LHON should still be considered even in older female patients presenting with unilateral acute visual loss when microangiopathy is seen. In such cases, molecular testing is effective in confirming a diagnosis of LHON.