Immature ovariectomized female rats primed with estradiol or without estrogen priming were treated with epitestosterone i.p. After 7 h blood was collected and LH and FSH levels were determined. The dose-response relationship was a biphasic one. LH and less markedly FSH levels decreased under epitestosterone treatment with doses up to 10 mg, whereas at higher doses an increase of gonadotrophins was observed.