Mrs. L., twenty-nine years of age, is seven months married. Her menstruation set in when she was fifteen years of age and was always regular of about six days’ duration. At that time she began to satisfy herself by manusturpation and found some libido in the manipulation. But soon she read in a book about the ill effects of this practice and stopped it. In the beginning of her married life coitus caused her great pain, which diminished by degrees after a few weeks. At present, coition causes her only disgust. The day after she feels tired and weak. The examination shows a feminine habitus, breasts well developed, clitoris normal. The hymenal rests are very sensitive to the touch. The painful sensation and the feeling of disgust increase when the anterior vaginal wall is touched. The uterus is enlarged to the size of a goose-egg, the cervix is soft, and the external os narrowly closed. Diagnosis, two months’ pregnancy. In this case some traces of libido were present at the time of puberty, which later on entirely disappeared. In some cases the patient is very prolific, as the following history shows: The author recently performed a perineorrhaphy on an otherwise healthy woman, mother of five children, who confided in him that she has never experienced the slightest libido in intercourse. Yet, she added, if her husband would not take precautions, she would give birth to a child every year, as was the case in the beginning of their married life. Anaesthesia in women is, as a rule, due to inexcitability of the genital nerves and to lack of excitation at the centre of libido. Sometimes anatomical anomalies of the genitals may cause impotence of libido. The integrity and the free exercise of the generative organs are necessary for the integrity of the libidinous feeling, although sexual pleasure is experienced at the nervous centres, and the generative organs play only a secondary part. The vaginal bulbi and their muscle, the constrictor cunni, the intermediary net of veins between the bulbs and the clitoris, and the free part of the latter, the glans of the clitoris, must functionate normally in order to give full satisfaction in intercourse. Hence diminution or extinction of the sense of libido will be caused by castration, degeneration of the ovarian glands, marasmus, sexual excesses and overindulgence in alcoholic beverages or cocaine. In the following case the erotic feeling increased in such a degree after the castration, probably through the extinction of the libido, as to deceive the family physician and lead him to make the diagnosis nymphomania.