Purpose : This study was carried out to investigate the effects of Gamigwichulpajing-Tang(GGT) on the development of experimentally-induced endometriosis in rats. Materials and Methods : Endometriosis was induced in rats by auotransplanting uterine tissue to the peritoneum and devided them into three groups: (1) sham-operated group(n=8), (2) surgically induced endometriosis and untreated control group(n=8), (3)surgically induced endometriosis and GGT treated group. GGT(700mg/head) was orally administrated for 15days after operation. Then we measured the body weight, the volumes of endometriotic implants, the weight of uterus and ovary, and investigated the content of cytokines(MCP-1, $TNF-{alpha}$, $IL-l{eta}$) in serum and ascites. Histopathology, immunohistochemistry for COX-2, and histochemistry for mast cell in transplanted uterine tissue were performed. Results :- The $volume(mm^3)$ of endometriotic implants in GGT-treated group$(53.50;{pm}18.63)$ was significantly decreased(p<<0.01) compared with control group$(404.50{pm}317.68)$. - The content(pg/ml) of MCP-1 in ascites in GGT-treated group$(4265{pm}108)$ was significantly decreased(p<<0.001) compared with control group$(8632{pm}1245)$. - The content(pg/ml) of $TNF-{alpha}$ in serum in GGT-treated group$(64.5{pm}21.6)$ was significantly decreased(p<<0.05) compared with control group$(147.1{pm}78.2)$. - The content(pg/ml)- of $TNF-{alpha}$ in ascites in GGT-treated group$(738.3{pm}502.4)$ was significantly decreased(p<<0.05) compared with control group$(1245.2{pm}362.2)$. - The percentage(%) of positive epithelial layers for COX-2 in GGT-treated group$(22.9{pm}9.3)$ was significantly decreased(p<<0.001) compared with control group$(50.2{pm}8.2)$. - The number of mast cells in adjacent tissue of transplanted uterine tissue in GGT-treated group$(61.4{pm}13.9)$ was significantly decreased(p<<0.001) compared with control group$(109.3{pm}30.2)$. - The number of mast cells in stroma of transplanted uterine tissue in GGT-treated group$(9.4{pm}2.7)$ was significantly decreased(p<<0.001) compared with control group$(26.0{pm}7.7)$. - Histopathologically, proliferation of endomeuiotic epithelia and stroma, and infiltration of inflammatory cells in transplanted uterine tissue of GGT-treated group were weakly observed than those of control group. Conclusion :On the basis of these results, we concluded that Gamigwichulpajing-Tang have inhibiting effects on the development of transplanted uterine tissue. And these effects may be related with decreased Production of MCP-1 and $TNF-{alpha}$, decreased expression of COX-2, and decreased infiltration of mast cells by administration of Gamigwichulpajing-Tang.