The object of our investigation was to determine what, if any, was the relation of the basal metabolic rate to the various stages and types of cardiac decompensation. An effort was to be made to follow these cases through from the time of admission to the hospital to the time of discharge, and to correlate the clinical and laboratory findings in an attempt to arrive at definite conclusions and deductions for the purpose of utilizing basal metabolic readings as aids in the diagnosis, management and prognosis of decompensated heart cases, very much after the manner of such determinations in the dysfunctions of the thyroid gland. Whereas there are numerous reports relating to the basal metabolism in diseases of the thyroid gland, in particular, and to a lesser extent in the various fevers, anemias, nephritis and obesity, comparatively little is to be found regarding the basal metabolic rate in heart muscle