The mitochondrial encephalomyopathies caused by a disorder in the mitochondrial DNA structure are rare multisystem diseases. MERRF ( myoclonic epilepsi, ragged-red fibers ), MELAS ( mitochondrial ensefalomyopathy, lactic acidosis, stroke-like episodes ) and KSS ( Kearns-Sayre Syndrome ) are the well known mitochondrial encephalomyopathies. There are limited reports about their neuroradiological findings. In Kearns-Sayre Syndrome basal ganglionic calcifications are often seen in CT, but only in a few case reports hyperintens lesions in the brain stem, cerebellum and diencephalic stuctures on T2- weighted MR images are demonstrated. In this study we discussed a KSS patient with his clinical, MRI and pathological findings.