Administration of 3 type KGCs [recombinant human granulocyte colony-stimulating factor (rhG-CSF)] to mice with cyclophosphamide (CPA)-induced neutropenia for 4 consecutive days from the day after the CPA dosing (100 mg/kg) resulted in a dose dependent increase in the peripheral blood neutrophil count 6 hours after the final KGC injection. Within the KGC dose range of 0.1 to 40$mu$g Per mouse Per day, there was a sigmoidal relationship between the logarithm of the dose and the peripheral blood neutrophil count (relative value for neutrophil count of the basal dose) in the treated mice. The sigmoidal relationship of test KGC preparations shows that there is a saturation point in terms of efficacy. Compared with e(fact of KGC-Orange, Green, and Blue, KGC-Orange recovers neutrophils more effectively than the others do.