Many of the symptoms of neurocirculatory asthenia are so similar to those found in hyperthyroidism, that the theory that this condition is a latent or a very mild thyrotoxicosis has often been advanced. Goetsch has employed epinephrin, given subcutaneously, as a test for latent hyperthyroidism. The detailed technic employed is described by Peabody1 in a report on the effects of epinephrin on soldiers with irritable heart. I performed the same test in a series of twenty-one consecutive cases in June, 1918,2 and it is these that I wish to report. The test, in short, consists of subcutaneous injection of 0.5 c.c. of a 1: 1,000 epinephrin solution, with subsequent observations of the pulse rate, blood pressure, tremor, nervousness and throbbing of the blood vessels. Since the systolic blood pressure of these patients is so very labile, they are allowed to rest on a bed until the blood pressure readings have