Modern endocrinology is no longer based on a collection of syndromes often notable only for their peculiarity. It deals with metabolic processes in the human body that are of the utmost interest to every branch of medicine.Careful clinical observations in endocrine diseases can, with the lucidity of an experiment, throw useful light on physiologic and patho-physiologic phenomena in the human organism.The purpose of the present work is to give an account of a typical and not particularly rare endocrine disease, and to propound certain viewpoints that have emerged from a study of such a case. In the first place, the influence of endocrine factors on blood pressure and renal function will be discussed. No exhaustive report of this case will be given. Only the details that serve to illustrate the particular problems concerned here will be set forth.A salesman, born in the year 1894, observed the first symptoms of his disease in 1936. In a few months, he lost considerable weight, had no growth of beard, and the pubis and axillary hair disappeared, as well as that of the trunk and extremities. The testes soon became atrophied, libido greatly diminished, and the patient became impotent. X-ray examination of the sella turcica showed normal conditions. Blood pressure equalled 120/80 mm Hg, basal metabolic rate -14 % -5 %.During this first phase of the disease, the patient distinctly manifested a marked hypogonadism. He was treated with testosterone propionate, l ) This is part of an investigation aided by a grant from Karolinska Institutet, Stockholm. 9