Posthypoxic myoclonus (Lance-Adams' syndrome) is a rare complication of cardiorespiratory arrest. It has a better prognosis than other movement disorders secondary to brain ischaemia. We report a case of posthypoxic myoclonus in a 66-year-old woman after acute myocardial infarction and cardiopulmonary arrest. She had action and intention myoclonus, and these movements were also initiated by acoustic and pain stimuli. The origin of the myoclonus was probably subcortical, and it improved with clonazepam 2 mg t.i.d. We emphasize that early diagnosis is necessary in intensive care units in order to avoid misinterpretation of this syndrome and to start appropriate treatment.