AIM To study the regulation effects of Momordica saponins on endocrine function in senile mice. METHODS 15-month Kunming mice (female), were divided into senile control group (SC), experimental group 1 and 2 (E1 and E2). 10 4-month mice were as young control group (YC). All mice were fed with general foodstuff, SC and YC drank tap water, while two experimental groups drank tap water supplied to 100 mg/L and 200 mg/L Momordica saponins respectively. Serum was assayed after 5 weeks. At the same time, levels of estrogen receptor and its mRNA were assayed in cultured thymocyte from 12-month rat. RESULTS Serum ACTH and estradiol levels declined markedly in senile mice compared with young mice. ACTH levels increased in some extent in two experimental groups, while there had significant difference only in E2. Serum estradiol increased obviously, but there was no significant distinct between E1 and E2. The most important was that ER levels increased obviously, and there was no any change of ER mRNA levels in rat thymocyte cultured in medium contained different content of Momordica saponins. CONCLUSION Momordica saponins could improve endocrine function in senile mice by increasing ACTH level and expression of ER.