A 6-year-old female with Leigh syndrome associated with a T-to-C mutation at nucleotide 8993 of mitochondrial deoxyribonucleic acid (T8993C) was treated with dichloroacetate, once during the first acute deterioration after a febrile illness and another time when she demonstrated subacute regression without precipitating events. Dichloroacetate reversed the clinical course on both occasions, and diffuse lesions in the midbrain revealed on magnetic resonance imaging during the second episode disappeared completely. However, dichloroacetate could not prevent the second acute deterioration associated with a febrile illness that occurred during the second treatment. Thus dichloroacetate treatment, although limited, was effective for T8993C-associated Leigh syndrome.