Clinical courses and investigations in 4 patients with inappropriate lactation and amenorrhoea of different aetiologies (pituitary tumour, "empty sella" syndrome, del Castillo syndrome and hypothalamic lesion due to histiocytosis-x disease) are reported. Basal serum immunoreactive prolactin (HPr) was normal in the patient with "empty sella" syndrome but subnormal after intravenous synthetic thyrotrophin releasing hormone (TRH) administration. In the 3 other patients HPr levels at basal and during TRH administration were high. Highly increased serum HPr levels were reduced after trans-sphenoidal removal of a prolactin producing tumour and a normal pregnancy occurred. Clomiphene citrate failed to increase serum luteinizing hormone (LH) levels or oestrogen excretion in the patient with histiocytosis-x disease who had a posterior hypothalamic lesion but intact anterior pituitary. Absent growth hormone (HGH) secretion during stimulation studies was also associated with the posterior hypothalamic lesion.