The proliferation of the endometrium in the first half of the normal cycle is caused by the follicular hormone. The transformation into the secretion phase in the second half is caused by the hormone developed by the yellow substance of the corpus luteum. The term “menstrual” bleeding must be preserved for the discharged endometrium which has been proliferated first by the follicular hormone, and then transformed into the secretion phase (pregravid phase) by the corpus luteum hormone. The growth of the uterus in childhood and its pubescence depends on the follicular hormone (vegetative activity of the ovary), just as does the preservation of turgor in the genitals of the puberal woman. Many years ago, cyclic genital activity in the castrated animal was first produced by the injection of hormone, and this effect is now employed as a test for ovarian hormones. I succeeded eighteen months ago in producing complete menstruation in the castrated woman. The size of the doses of ovarian hormones administered is the important factor. In numerous experiments I have shown that—according to our present conceptions—very large doses of follicular hormones are required to produce the proliferation phase of the endometrium. The required dose is about 200,000 mouse units (= 1 million international units). For transformation of the proliferated endometrium into the secretion phase, 35 rabbit units of corpus luteum hormone are needed. The doses of follicular hormones up to now employed in therapeutics do not exert any traceable influence on the endometrium of the castrated woman. Neither have I noticed, that with doses of 600 or 1,000 mouse units, a shrivelling of the uterus which is due to long lasting functional troubles may be done away with. I have therefore proceeded to treat serious hormonal affections of the ovaries with very large doses of ovarian hormones. This paper reports on: (a) The effect of the follicular hormone on the hypoplastic uterus, in primary and secondary amenorrhœa; (b) spontaneous regulation of the cycle in secondary amenorrhœa also after treatment; (c) the treatment of symptoms produced by castration and at the climacteric; (d) the treatment of genital bleeding with corpus luteum hormone.