Abstract: The Plasmodium yoelii nigeriensis gametocyte carrying mice were administered intragastrically with primaquiue 1.25mg/kg and 1.95mg/kg, 8h after treatment, the number of gametocytes in the blood had been reduced to 1/2. The morphology of some gametocytes appeared abnormal. The decrease of number of ookinetes, the infective rate and infetive degree of oocysts and gland infection rate was proportional to the increase of dosage of primaquine and infection time of mosquitoes, with the vacuolation and shri nkage of some ookinetes and oocysts.

Key words: Plasmodium yoelii nigeriensis, gametocyte, ookinete, oocyst, sporozoite, primaquine