MELAS syndrome is one of several mitochondrial-inherited encephalomyopathies distinguished from the others by its unique stroke-like episodes. A case is presented that illustrates the importance of acknowledging the heteroplasmic nature of this disease when making its diagnosis. The mitochondrial DNA (mtDNA) point mutation characteristic of MELAS was eventually detected by analysis of a muscle biopsy specimen after initial studies of a serum sample were negative for the same genetic defect. Other diagnostic features of MELAS syndrome are described; these include characteristic computed tomography (CT), magnetic resonance imaging (MRI), angiography, single photon emission computed tomography using N-isopropyl-p-[123-I]-Iodoamphetamine (IMP-SPECT), and pathological findings. Finally, various theories regarding the etiology of stroke in MELAS syndrome as well as available treatment options are discussed.