Abstract: Objective To investigate the effect of Cyclophosphamide on the white blood cell of C. parapsilosis infectted mouse. Methods ICR mouse were given cyclophosphamide once a day for 3 days before C.parapsilosis inoculation .The other mouse were injected with C.parapsilosis, cyclophosphamide and N.S respectively as control groups. Then the mouse blood was collected and the blood were analysised. Results After C.parapsilosis inoculation, Cyclophosphamide treatment resulted in an immediate depression of peripheral blood leucocytes, with WBC and lymphocyte rebounding quickly to normal and rising throughtout the 2-week observation period, while mouse not treated with cyclophosphamide did not. And the cyclophosphamide model mouse, the number of WBC down quickly after inoculation， while up on the 5 day and recover to normal on the 11 day. Conclusion The WBC can be depressed effectively in some times with Cyclophosphamide; Cyclophosphamide can result in immunosuppression and play an important part in C.parapsilosis murine model.

Key words: Leukocyte, C.parapsilosis', Cyclophosphamide, ICR mouse