The recent development of radioimmunoassay methods for the measurement of human prolactin has increased the chance of diagnosing the amenorrhea with hyperprolactinemia or prolactin-secreting pituitary microadenoma. In this paper two infertile women showing anovulatory amenorrhea associated with prolactin-secreting pituitary microadenomas were described.<BR>Case 1. Y.K. was 27 years old. she had menarche at 13 years of age and irregular periods until she was 27 years old. Her basal body temperature curve showed mono-phasic, and plasma FSH and LH levels were within normal range. Although she was treated with clomiphene 100mg daily for 5 days or 150mg daily for 5 days, no ovulation was induced. A subsequent investigation showed slight galactorrhea and significant elevation of the plasma prolactin levels (340-500ng/ml). Roentgen examination of the sella turcica showed an asymmetrical floor suggesting a existence of pituitary microadenoma. A simultaneous intravenous injection of synthetic LH-RH 100μg and TRH 500μg indicated that the LH and FSH response were within normal range but prolactin response was very large. Following treatment with bromocriptine 5mg daily for 14 days, she had anovulatory menstruation. With the treatment of bromocriptine 7.5mg daily plasma prolactin was suppressed within normal range (20-30ng/ml). And then she showed ovulation and conceived. From the 9th week of gestation until midtrimester she had moderate headache. Examination of visual fields in 25th week of gestation was almost normal. Otherwise the course of her pregnancy was uneventful. At term she spontaneously delivered a normal boy weighed 3380g. Her weight gain during pregnancy was small (4.50). Lactation was sufficient for the child's nutrition. After parturition 13 months have passed until today, she still showed a persistent slight galactorrhea.<BR>Case 2. Y.O., age 28 had menarche at 14 years of age, and then irregular periods. Since 1975 she was treated with sexovid or clomiphene without result. She had no galactorrhea. Her plasma FSH and LH levels were within normal limit, but prolactin levels showed significant elevation (110-240ng/ml). Roentgen examination _of the sella turcica with plain and polytomography revealed slight bony erosion with asymmetrcal floor suggesting the existence of microadenoma. Neurologic evaluation and EEG were normal. A simultaneous intravenous injection of synthetic LH-RH 100μg and TRH 500μg indicated that the LH and FSH response were deficient, but prolactin response was moderate. Following treatment with bromocriptine 5mg daily for 7 days and then 7.5mg daily, plasma prolactin levels were suppressed to the range of 20-36ng/ml. Following 4 week administration bromocriptine, ovulation occured following a single injection of progesterone 50mg. At this ovulation time she conceived. From the early part of pregnancy until 18th week of gestation she sometimes had slight headache. In 25th week of gestation examination of visual fields was normal. Otherwise the pregnancy passed uneventfully. At term she spontaneously delivered a normal boy weighed 3230g. Her weight gain during pregnancy was small (6kg). Lactation was not sufficient for the child's nutrition. After parturition she has no menstruation until today for 1 year.