A gonad endocrine survey on 46 Congolese patients (15 women and 31 men) with parasitologically confirmed trypanosomiasis found amenorrhoea in 60% of the women and impotence in 70% of the men. The basic gonad endocrine examination showed a decrease in oestradiol levels in about 65% of the women. Both amenorrhoea and low oestrogen levels were observed in the second phase (P2) of the disease, but low oestrogen levels were sometimes noted in the first phase of the disease (P1). In the men, about 50% of the cases (P2) showed a decrease in testosterone. However, as in the women, the variation of testosterone was also observed in the first phase (P1). A static and dynamic examination of the hypothalamic-pituitary-gonadal axis was undertaken in order to investigate the origin of these hypogonadisms. A supra - or extra-hypophyseal origin is discussed.