A case of episodic delirium with incapacitating myoclonus associated with therapeutic doses of phenelzine is described. No evidence of epilepsy was found. The delirium and the myoclonus remitted rapidly after phenelzine was stopped and treatment with a benzodiazepine was started. No previous reports of the association of phenelzine with myoclonus and delirium have been found. The possible neurophysiology of the association is explored. Treatment with phenelzine should be reviewed if myoclonus occurs.