Abstract: In order to reduce the side effect of gossypol,gossypol was used in conbination with steroid hormones so that the dose of both drugs can be reduced,Silastic capsules containing testosterone(T)+estradiol(E) were implanted under the skin male wister rats for 8 weeks,After removing the implants,testosterone was given orally at the dose of 15mg·kg^-1 which is only 50% of the usual antifertility dose.Mating tests showed that the male rats became infertile.Microscopic examination of the heart,liver and kidneys showed no pathologic changes.The treated rats gained body weight as well as the controls.The fertility of the treated rats recovered four to five weeks after treatment.Thus,gossypol in combination with testosterone and estrogen exhibited a low degree of side effect and high antifertility activity.