In some cases of hypogonadotropic euriuch-oidism or panhypopituitarism in the male, development of secondary sex characteristics and spermatogenesis may be induced by treatment with testosterone alone. Chorionic gonadotrophin, containing varying quantities of follicle-stimulating as well as luteinizing hormone, may induce development of secondary sex characteristics and N retention through stimulation of the Leydig cells and,, if continued long enough, may cause maturation of the spermatozoa. Chorionic gonadotrophin with, or followed by, testosterone apparently will do the same thing. Once these developments have occurred,continued treatment apparently is not always necessary.