Abstract: Mice (C57BL, ICR/JCL and Kunming strain) and rats were infected by intravenous inoculation of sporozoites of Plasmodium berghei ANKA strain via tail vein. The pre-erythrocytic schizonts were found in hepatocytes 46 to 47 hrs after injection. They were usually spherical, sometimes a little oval, in shape and the mean size was 8.07×16.13-25.80 ×30.54μm. It seemed clear that the number of pre-erythrocytic schizonts was larger in rats than in mice.