ObjectiveWe report two family and one sporadic case with dyssynergia cerebellaris myoclonica, investigate the clinical and neural electrophysiological features. MethodsThe proband and sporadic patient was examined by clinical, neuroimaging, video-EEG and synchronous electromyography. ResultsThere were 6 patients with dyssynergia cerebellaris myoclonica of the 27 family members in the first family(3 male and 3 female). There were 4 patients with dyssynergia cerebellaris myoclonica of the 20 family members in the second family(2 male and 2 female). All patiens had disproportionately myoclonus, epilepsy and progressive cerebellar ataxia. EEG showed bursts of spike-slow wave, polyspilke-slow wave distributing in the bilateral brain both in ictal and interictal period, sometimes it is especially in central, parietal and frontal area. EEG showed bursts of spike-slow wave, polyspilke-slow wave distributing in the central, parietal and frontal area in interictal period. Pathology of the skin and muscles are normal. ConclusionThe diagnosis of dyssynergia cerebellaris myoclonica was mainly based on typical clinical manifestations, brain MRI and EEG changes.Long time video EEG and synchronous EMG is important for the diagnosis. Skin and muscles pathology can be normal.