Myoclonic epilepsy of Lafora (EPM2) is a severe autosomal recessive disorder. The onset in adolescence, generalized seizures, severe myoclonus, dementia and a rapid malignant course with death in 4-8 years after the onset are characteristic features of EPM2. The disease has a specific pathological feature, intracellular polyglucosan inclusions (Lafora bodies) in the brain, liver, skin and muscles. Two genetic forms are known, one of which (EPM2A) is caused by mutations in the laforin gene and another (EPM2B) - by mutations in the malin gene. We report a case of EPM2A in a 17-year-old girl of mixed Russian-Ukrainian ethnicity. The disease lasted for almost four years by the time of the examination but the girl still had no dementia. A previously described laforin mutation Tyr86Stop in the homozygous state was detected and Lafora bodies were found in the skin and muscles. Various anticonvulsants produced no effect or a slight and unstable effect. In the following several months, the disease progressed quickly, the girl became severely disabled and demented and died in 19 years old, 5,5 years after the disease onset. This is a first Russian case confirmed by DNA testing.