The authors present a case-report of the MELAS syndrome in a 20-year-old woman. Suspicion that this syndrome is involved was aroused besides the typical clinical picture also by the finding of laterally changing ischaemic lesions, manifested in particular in the area of the lobes and apparent during repeated examinations by magnetic resonance. The diagnosis was confirmed by molecular genetic examination which provided evidence of the presence of heteroplasmic point mutation of the type 3243 AG in the gene tRNA leu of mitochondrial DNA in muscle tissue and blood.

        Key words: MELAS syndrome, mitochondrial encephalomyopathy, MR imaging