28 female uraemic patients treated by chronic haemodialysis were studied. Of these patients, 6 had regular cycles, 6 irregular cycles, 7 were amenorrhoeic and 9 post-menopausal. Plasma gonadotropins (FSH and LH) were determined in all patients. Plasma concentrations of oestradiol and progesterone were determined only when of possible interest. LRH stimulation test was performed in 5 amenorrhoeic patients. In 19 pre-menopausal women baseline plasma FSH values were always normal, but LH concentrations were above normal in 5. In all 9 post-menopausal women both FSH and LH were markedly higher than in the pre-menopausal patients., either healthy or uraemic. Persistent oestrogen activity was found in the 6 regularly menstruating women as well as in the 5 women with oligomenorrhoea. Luteal phase plasma progesterone was in the low normal range in 3 patients and was markedly depressed in the others. A prolonged rise in LH and to a lesser extent in FSH was observed in 4 of the 5 patients studied after 100 micrograms of LRH were administered intravenously. These results suggest that the defect underlying gonadal dysfunction in uraemic women treated by chronic haemodialysis is mainly of suprahypophyseal origin.