The reaction of PRL, TSH, GH, LH and FSH has been studied after the administration of TRH and LHRH to 15 acromegalic women of fertile age. According to the presence or absence of menstruation the patients were divided into 2 groups: 8 patients menstruated regularly, 7 had secondary amenorrhoea. The results of the two groups were compare with each other and to findings in a group of healthy controls (9 women). It was found that in secondary amenorrhoea basal PRL values significantly exceeded those registered in the menstruating group and in the controls. PRL reaction was similar in the controls and the secondary amenorrhoea group, but the menstruating patients showed lower values than those of the control group. TSH release did not differ in the three groups. In secondary amenorrhoea paradoxical GH-reaction after TRH-LHRH in the 15th minute significantly exceeded the value of the menstruating group and its whole course pointed to a more intensive reaction. In secondary amenorrhoea both basal LH and FSH secretion as well as LH and FSH release fell far below the values of the menstruating group. The onset of amenorrhoea was not related to the duration of acromegaly. Disturbances of gonadotrophin secretion may be induced by disorders of regulatory mechanisms as well as by the damaging effect of the adenoma on normal pituitary tissue.