In order to evaluate the anti-tumor and synergic effect of Soonkiwhajungtang with doxorubicin, the inhibitory concentration(IC), IC50 and IC90 of single use of doxorubicin and Soonkiwhajungtang with their concomitant treatment against Colon-26(Murine Rectum Carcinoma) was observed using MTT(Microculture Tetrazolium test) assay. In addition, their anti-tumor effects were also observed in the xenograft nude mice models against 3LL cell lines. Soonkiwhajungtang may only mimic direct anti-tumor effects against 3LL cell lines, but signs of worsening induced by implantation of tumor cell lines generally decreased, while the total WBC and lymphocyte numbers increased. Therefore, experimentation suggests that Soonkiwhajungtang extracts reduced the critical toxicity of doxorubicin, and that Soonkiwhajungtang extracts have favorable synergic effects when combined with doxorubicin.