Purpose : Taraxaci Herba is a herb with an effect on extravasated blood and is widely used in gynecology. This study examined the effects of Taraxaci Herba on endometriosis. Methods : Rats with surgically induced endometriosis were given an oral dose of Taraxaci Herba for 40 days. The size of the ectopic uterine implants at the serosal wall and the concentration of progesterone, estradiol, tumor necrosis factor-${alpha}$(TNF-${alpha}$) and interleukin(IL)-2, 4, 6, and 10 in the blood were examined and compared with the control group. Results : The size of the ectopic uterine implants in the treated group was much smaller than that in the control group. The estradiol concentration was significantly lower in the experimental group than in the control group. The IL-10 level was higher and the TNF-${alpha}$, IL-2 and IL-4 concentration were lower in the experimental group than in the control group and there was statistically significant difference. There was no significant difference in the IL-6 level between the experomental and the control group. Conclusion : These results indicate that Taraxaci Herba reduces the size of ectopic uterine implants at the serosal wall and inhibits the growth of ectopic uterine implants. This suggests that Taraxaci Herba is an effective treatment for endometriosis.