Purpose : To observe the effect of retention enema therapy Gamihongdeung-tang on experimentally induced endometriosis. Methods : Rats with surgically induced endometriosis were administered in Gamihongdeung-tang rectally. After treatment for 40 days, the serum concentrations of progesterone, estradiol, tumor necrosis factor-${alpha}$(TNF-${alpha}$),　interleukin(IL)-2,　IL-4, IL-6 and IL-10 were measured. Results : The size of the ectopic uterine implants in the treated group was much smaller than that in the control group. The concentration of estradiol was significantly lower in the experimental group than in the control group. The IL-4, IL-6 levels were significantly lower in the experimental groups than the control groups. TNF-${alpha}$, IL-2 levels were lower and IL-10 level was higher in the experimental groups than in the control groups but the difference was not significent. The progesterone level was similar in the experimental and control group. Conclusion : These results indicate that Retention enema therapy with Gamihongdeung-tang reduces the size of ectopic uterine implants at the serosal wall and inhibits the growth of ectopic uterine implants. This suggests that retention enema therapy with Gamihongdeung-tang is an effective treatment for endometriosis.