[en] Irradiation of 26 MeV electron rays produced by Betatron was applied to the back of rabbits at the field of 14 cm phi in doses of 100 rads, 300 rads, 600 rads and 1000 rads each at one time. Hematological change resulting from the difference in irradiation dose was examined during one month. Erythrocyte count showed a slight decrease (approx. 8--14%) in groups of more than 600 rads irradiation. Leucocyte count showed a decrease at first in groups of more than 300 rads irradiation, then showed a temporary increase which was followed by decrease again. Thus, the so called wavy fluctuation was observed. Especially, in the 1000 rads irradiation group a remarkable decrease (65%) was observed 3 hours after irradiation. One day thereafter, a temporary increase (55%) was observed. This was followed by decrease again. Change in the values of pseudoeosinophils resembled that of the leucocyte count for the most part. Lymphocytes showed a decrease in each group and the rate of decrease was especially high in proportion to the irradiation dose. (JPN)