Cyclophosphamide is used to treat a variety of tumors. However, the success of the treatment is limited due to severe myelosuppression caused by cyclophosphamide. Administration of cyclophosphamide could significantly decrease white blood cells (WBCs), platelets, red blood cells (RBCs), as well as hemoglobin level. The aim of this research is to investigate the protective role of Shenfu injection against cyclophosphamide induced myelosuppression. The results showed that Shenfu injection can markedly enhance the level of WBCs, platelets, RBCs, and hemoglobin of myelosuppressed rat. The level of WBCs, platelets, RBCs, and hemoglobin were increased by 70%-100%, 80%-90%, 10%-20% and 10%-20%, respectively. Furthermore, the protective role of Shenfu injection against myelosuppression was confirmed by the microscopic observation of bone marrow sections. In conclusion, Shenfu injection has a potential protective effect against cyclophosphamide-induced myelotoxicity.