THE INITIAL investigations of monoamine oxidase (MAO) inhibitors, commonly used to treat depression reactions, were favorable,1,2 although adverse reactions such as dryness of mouth, postural hypotension, dizziness, and central nervous system disturbances occurred.2,3 There have been several recent reports of severe hypertensive crises in patients taking drugs of this group.4-13 A total of 22 fatalities from overdosage has been recorded.14-21 Therapy for the overdosage of MAO inhibitors has consisted of withdrawal of the drug and symptomatic measures. The use of hemodialysis for removal of tranylcypromine (Parnate) sulfate, a potent MAO inhibitor, has not been previously reported.15 Report of Case A 15-year-old white girl ingested 350 mg of tranylcypromine sulfate during an episode of psychic depression. Within six hours she became irrational and developed generalized muscular hyperactivity. Twenty-three hours after ingestion of the tablets, she was admitted to the Oklahoma University Hospital, Oklahoma City. Her blood pressure was 100/60 mm Hg;