In order to increase familiarity with the diagnostic evidence of hypogonadism in men, twelve postpubertal castrates were subjected to careful clinical and laboratory studies, including bio-assays for the gonadstimulating principles of the urine, and another substance from urine, presumably a testicular hormone which promotes comb growth in capons. SYMPTOMS Nervous and Vasomotor Symptoms.— The nervous and vasomotor symptoms of these castrated men constituted their most outstanding complaints. Unilateral castration did not give rise to any symptoms except a temporary diminution of libido in two cases. Complete castration, either by the simultaneous removal of both testes or by the removal of a single remaining gland, produced nervous and vasomotor disorders as early as the third day after operation. Nervousness was a major complaint of four patients at the time they were studied, although nine had experienced it at some time for varying periods after castration. The usual history was that the