Myoclonic jerks are sudden, brief, involuntary simple movements caused by a pathological increased excitation of motor neurons. Symptomatic myoclonus was the most frequent etiology, followed by epileptic and hereditary or sporadic myoclonus. A useful basic distinction based on etiology differentiates physiological, essential, epileptic and symptomatic myoclonus. Physiological myoclonus most often is not disturbing and does not need to be treated. Epileptic myoclonus is usually defined by the presence of myoclonus in the setting of epilepsy. Symptomatic therapy is also comparable, and the transition from myoclonus to epileptic myoclonus is blurred. Myoclonus in autosomal recessive, rapidly progressive Lafora body disease is usually mild and infrequent but worsen continously. Neurophysiology helps to determine the origin of myoclonus. Ideally, treatment of myoclonus can be based on its physiological classification. The choice of drug can be based on neurophysiological classification of myoclonus.