Objective : The objective of this study is to investigate the inhibitor effects of an traditional oriental herb, Sophora flavescens on the hepatic and renal side effects of chemotherapy by using B16-BL6 melanoma-injected C57BL6 mouse tumor model. Methods : In this study, the effects of an traditional oriental herb, Sophora flavescens, on the side effects of chemotherapy were studied using B16 melanoma-injected C57BL6 mouse tumor model. Results : Sophora flavescen has significant effect on the reduction of the side effects of chemotherapy. Sophora flavescen recovered the reduction of WBC and RBC during cisplatin chemotherapy. Water extract of Sophora flavescens significantly inhibited cisplatin-induced increase of serum blood urea nitrogen (BUN) which is a good indicator of renal toxicity. Sophora flavescens extract does not decrease the anti-tumor activity of cisplatin showing that it can selectively inhibit side effects of anticancer drugs preserving beneficial effort. Conclusion : Theses results suggest a possibility that Sophora flavescens extract can be used for cancer patients for the reduction of the side effects and improving the quality of life during chemotherapy of cancer patients.