Purpose. To report a case of a young patient with a clinical condition suggestive of Leber's hereditary optic neuropathy (LHON) confirmed by genetic testing. Material and methods. We present a case of a 21-year-old Caucasian male with bilateral visual loss. The patient complained of visual loss, initially in the right eye and two weeks thereafter in the left eye. Ophthalmological examination revealed visual acuity of 20/ 400 in both eyes, anterior segment of normal appearance, normal direct and consensual pupillary light reflexes, and absence of a relative afferent pupillary defect. Fundus examination demonstrated bilateral protruding, hyperemic, with blurred margins in the nasal quadrant papilla and reduced excavation, tortuous vessels, peripapillary telangiectasias. The optical coherence tomography (OCT) revealed bilateral increase of the retinal nerve fiber layer (RNFL) thickness and ganglion cell layer - inner plexiform layer complex (GCL-IPL complex) severely thinned. Results. The clinical suspicion of Leber's hereditary optic neuropathy was confirmed by the 3460 mutation, which was identified on blood mitochondrial analysis. Meantime, the visual acuity decreased to CF in both eyes. We initiated treatment with idebenone (300 mg T.I.D.). After three months of follow-up, visual acuity was CF in both eyes, bilateral pupillary light reflexes within normal limits and optic disc pallor was noticed in both eyes. Conclusion. No visual recovery was noticed after one year. We recommended that the idebenone treatment was continued and the patient was followed-up further.