Fuzheng Yiai Infusion is an effective remedy for micro - residual leukemia (MRL). It yields marked mitigation on the geneval condition of the patient and prevents complications by substantially improves the patients immunity, elevates the rate of total remission and living quality, prolongs the survival period. Studies on the indices including DNA index, rate of DNA non - uneuploid, ph' chromosome, and BCR/ ABL gene, showed that the recipe can inhibit or eliminate the actions of malignant clone. In vitro cultivation of cells proved that the recipe yields stimulating action on the proliferation of normal marrow cells, yet yields no stimulating action on leukemic cells. Animal experiments reveal this recipe markedly prolongs the survival period of MRL animal models.