Abstract: The effect of ginsenoside Rb₁ has been studied on sexual deficiencies induced by repeated hanging stress. Male mice were stressed by hanging once daily(9∶00 am～2∶00 pm) for 10 days(1～3 day hung for 2 h, 4～6 day hung for 3 h, 7～9 day hung for 4 h, 10～11 day hung for 5 h). On day 10, they were exposed to female mice treated with estradiol and progestone and their sexual benaviors (licking, mounting, mating) were assessed at 7∶00～9∶00 pm. The repeated hanging stress was found to reduce sexual behaviors and decrease plasma testosterone level in mice. Treatments with ginsenoside Rb₁(2.5,5,10 mg·kg^-1,ip) 30 min before each stress prevented the repeated stressinduced sexual deficiencies and raised plasma testosterone level. The mechanism of the protective action of ginsenoside Rb₁ may be attributed to its action in maintaining normal plasma tesosterone level.