This chapter has been written with a purpose to introduce the jerky movements known as myoclonus to the readers. Myoclonus is quite common and often it is under or misdiagnosed. Careful eyes will pick up the abnormal movements and help in the early diagnosis and management. Diagnosis is clinico-electrophysiological. EEG is helpful to exclude the epileptic myoclonus and usually negative in cases with essential and spinal myoclonus. The diagnosis is very important and often inexperienced doctor makes a clinical diagnosis of functional disorders unless they are aware of this condition. Combined EEG and EMG recording helps to sub-classify the cortical and brainstem origin of the myoclonus which has been discussed in chapter on electrophysiology of movement disorders. Treatment is commonly symptomatic and definitive in limited conditions such as iatrogenic, toxic, metabolic and rarely paraneoplastic causes.