Objective To study the seasonal variation influences on reproductive functions in female rhesus monkey. Method\ Seasonal biological variations in skins,menstrual cycle,level of hormones were assasyed by random sampling of statistics method and radioimmune technique.Results\ 1.The periodic changes in sexual characteristics were demonstrated,including the sexual skins and normal menstrual cycles of all female rhesus monkeys during the breeding season.During the non\|breeding season some female rhesus monkeys displayed the sexual skins and abnormal menstrual cycles,a few female rhesus monkeys showed no menstrual cycles for a longer time.2.Gonadotropin and steroidogensis displayed significant cyclical secretion in the breeding period,while no significant cyclical secretion in the non\|breeding season.Conclusion\ It is suggested that female rhesus monkeys show remarkable sexual skins,menstrual cycles and hormones change between the breeding and non\|breeding seasons,which could lead to different reproductive functions of female rhesus monkey.