The therapeutic usefulness of iproniazid prompted the search for related compounds when hepatotoxicity was reported. One of the newer analogues developed is beta-phenylisopropylhydrazine (Catron), and the following case represents a hepatic reaction with a fatal outcome after its administration. A 65-year-old woman entered the Mount Sinai Hospital with a one-week history of jaundice. The patient, who had severe hypertension, had previously taken many drugs. Six weeks prior to admission she was given 18 mg. a day of beta-phenylisopropylhydrazine for two weeks; then therapy was maintained with 12 mg. a day in addition to chlorothiazide and reserpine. Her blood pressure of 240/120 mm. Hg, which was unresponsive to treatment with chlorothiazide. hydralazine, ganglionic blocking agents, and reserpine, was reduced to 160/90 mm. Hg after two weeks of beta-phenylisopropylhydrazine therapy, and she was symptomatically better. During the week preceding admission, after a total dose of about 600 mg. of beta-phenylisopropylhydrazine, she noted