Reference to theophylline-ethylenediamine first appeared in the literature twenty-two years ago.1Since that time a fairly large number of papers have described the pharmacologic and clinical effects of this drug. A member of the methyl-xanthine group of diuretics, it is a readily soluble combination of theophylline, 78 per cent, and ethylenediamine, 22 per cent. The active portion of this combination undoubtedly is the theophylline, the ethylenediamine being an innocuous preparation whose effects on frogs resemble those of the aliphatic narcotics.2The physiologic action of theophylline resembles closely that of caffeine. For the purposes of this paper, it is sufficient to recall that the xanthine derivatives act peripherally and centrally on the heart and blood vessels. Vasodilatation with sufficient stimulation of the heart to maintain blood pressure follows the administration of therapeutic doses of the drugs of this group. Sollmann3considers theophylline most powerful, theobromine next most effective