Much has been written of late, especially in the continental medical journals, as to the value of cardiazol (penta-methyl-tetrazol). It has been recommended especially in cases of acute cardiovascular collapse and respiratory failure. Glowing reports are appearing of its use in varied conditions, such as pneumonia, surgical shock, intrapartum asphyxia, auricular fibrillation, angina pectoris, diabetic coma, scopolamine depression and other conditions. The bulk of these reports, however, are of poorly controlled clinical observations made on a small number of cases, usually from three to six, when other stimulants had previously been given. It is our purpose in this paper to give a short summary of the pharmacology of cardiazol and to report some experimental work concerning the points for which it is most recommended. Camphor has long been used as a cardiac stimulant, especially in acute conditions and in moribund states. Lewin,1 in 1890, and Schwalb,2 in 1912, found it