A case of a young man with myoclonus in his right side after cerebral hypoxia is reported. This patient had cerebral hypoxia caused by injury in his left common carotid artery. After a few hours he had generalized convulsive seizures of tonic-clonic type and also a septic shock. As consciousness was regained, he developped action and intention myoclonus in his right-side. The EEG showed difuse typical myoclonus potentials. Clonazepan 8mg daily was used with good results. This is the first reference in the medical literature of the unilateral localization in the Lance-Adams syndrome. The authors think that in this case two abnormalities contributed to the cerebral anoxia: the common carotid artery injury and the sepctic shock.