Juvenile myoclonic epilepsy (JME) is an idiopathic primary generalized epilepsy of teenagers, characterized by massive myoclonic seizures. 18 patients were investigated. Myoclonic seizures first appeared at the mean age of 14 years and were characterized by short rapid abrupt involuntary jerks of extremities with the preserved consciousness. There were 2 types of myoclonic fits: massive seizures with symmetric jerks of extremities (33% of patients) and asymmetric asynchronous seizures of various frequency and intensity (67% of patients). In 50% of patients there were myoclonic seizures in leg muscles, in some cases patients fell down (myoclonic-astatic seizures). The authors emphasize the unusually high frequency of cases with myoclonic seizures combined with absences (66,7%) and generalized convulsions (83,3%) occurring on awakening. It is suggested that myoclonic component in the structure of absences may be an early sign of JME and predict development of myoclonic seizures.