Although there had been scattered reports in the literature about paroxysmal hypertension, in 1926 pheochromocytoma and its relationship to hypertension were unknown. Catecholamines were first isolated in 1898 by Abel, but it was not until 1929 that Rabin first demonstrated increased epinephrine content in the adrenal medulla [I]. The first successful resection of a pheochromocytoma was performed by Roux in Lausanne, Switzerland, in February 1926. The case of Mother Joachim represents, to the best of our knowledge, the first successful resection of a pheochromocytoma after Roux’s patient and certainly the first in the United States. Mother Mary Joachim was a 30 year old Roman Catholic nun from Chattam, Ontario, Canada. She was referred to the Mayo Clinic by J. H. Duncan of Chattam, who wrote in his referring letter, dated May 31,1926: “I feel much as Festus felt in sending Paul to Rome-not having any definite accusation against him . . . . She complains of weakness and also complains and very much fears recurrent attacks of gas, nausea and vomiting associated with severe headaches. . . . I believe that these attacks are due to an incompetent liver.” Dr. Duncan concluded, “I suggested to Mother that with your extensive and specialized machinery for diagnosis, you might readily find some pathological condition that I have missed.” Mother Joachim arrived at the Mayo Clinic on June 3, 1926, and was admitted to Saint Mary’s Hospital the following day for investigation and observation. During this period, which lasted until operation on October 11, many astute observations were made by both the attending physicians and the nursing staff. Daily recording of her blood pressure revealed levels of 100/70 to 280/190 mm Hg. The descriptions of her attacks were summarized and