THE CLINICAL SYNDROME associated with pheochrome tumors of the adrenal medulla has come to be a well recognized entity and a number of cases have been reported, some of which have been relieved by surgical removal of the tumor. Although paroxysmal hypertension has frequently been noted, it is not a sine qua non in the diagnosis. In our two cases persistent hypertension developed. Variations in blood pressure were present early in the course of observation in the first case and these persisted and were superimposed upon the constant hypertension in the second case. One of our cases was correctly diagnosed before operation and was cured by surgical removal of the tumor, while the second is from our records and was diagnosed at autopsy, having been considered clinically to be hyperthyroidism. Hypermetabolism was an outstanding feature in both cases Until the past decade, the vast majority of these tumors were found at autopsy and reported by pathologists. Brunschwig and Humphreys1 found 103 cases in the literature to 1940. These were mostly found at autopsy. McKenzie and MacEachern2 presented an excellent paper in 1938, at which time the' had collected 20 cases treated surgically. Since that time several additional surgical cases have been reported. Although the tumor is still uncommon, it is being recognized and properly treated much more frequently now than it was previously