The baboon (Papio cynocephalus anubis) is a well-established discriminative model for human reproduction as well as for studies of human schistosomiasis (mansoni). The present study examined the impact of experimental Schistosoma mansoni infection on ovarian hormones and prolactin in 28 female baboons (6-8 Kg). Serum concentrations of estradiol, progesterone and prolactin were recorded 2 and 11 weeks post secondary infection challenge dose (1000 cercariae). Lower than normal levels (serum estradiol < 50 pg/ml, serum progesterone < 1 ng/ml and serum prolactin < 2ng/ml) were found in the circulation, particularly 11 weeks after the challenge, when 20% of the animals had low hormone levels, which may be indicative of an anovulatory ovary. The results suggest that schistosomiasis may be a contributing factor to reduced fecundity among women in endemic regions.