Purpose : This study was performed to investigate the effects of Sobokchukeo- Tang(SCT) on the experimentally-induced endometriosis in rats. Materials and Methods : Endometriosis was induced via the surgical autotransplantation technique in rats. A laparotomy was performed and a $4;{ imes};4;mm$ of the right uterine horn was resected incised and sutured to the peritoneum. And the animals divided into control(n=8) and SCT-treated group(n=8). SCT(1,000 mg/head) was administered orally for 15 days after operation. The weights(body, left uterus, and ovaries) and concentrations of cytokines(MCP-1,$TNF-{alpha}$, $IL-l{eta}$) were measured. Histopathology, immunohistochemistry for COX-2, and histochemistry for mast cells of the transplanted uterine tissues were performed. Results : - The $volume(mm^3)$ of transplanted uterine tissues of SCT-treated group$(92.88{pm}41.89)$ was significantly(p<<0.01) decreased than the control group $(404.50{pm}317.68)$. The concentration(pg/ml) of MCP-1 in ascites of SCT-treated group$(5,256{pm}1,209)$ was significantly(p<<0.001) decreased than the control group$(8,632{pm}1,245)$. - The concentration(pg/ml) of $TNF-{alpha}$ in ascites of SCT-treated group$(521.8{pm}306.1)$ was significantly(p<<0.01) decreased than the control group$(1,245.2{pm}362.2)$. - The percentage of COX-2 positive epithelial layer in transplanted uterine tissues of SCT-treated group$(25.0{pm}7.3)$ was significantly(p<<0.001) decreased than the control group$(50.2{pm}8.2)$. - The number of mast cells in the stroma of transplanted uterine tissues of SCT-treated group$(16.5{pm}6.8)$ was significantly(p<<0.05) decreased than the control group$(26.0{pm}7.7)$. - The number of mast cells in the periphery of transplanted uterine tissues of control group$(71.3{pm}18.5)$ was significantly(p<<0.01) decreased than the control group$(109.3{pm}30.2)$. - Proliferation of epithelia, infiltration of inflammatory cells, and microanglogenesis in transplanted uterine tissues of treated group were weakly observed than the control group. Conclusion : From the above results, Sobokchukeo-Tang(SCT) has an inhibitory effect on the development of transplanted uterine tissue in rats and it is related to the decreased concentration of MCP-1 and $TNF-{alpha}$, and decreased expression of COX-2, and decreased infiltration of mast cells by administration of Sobokchukeo-Tang.