The authors reported the results of screening tests for hypocatalasemia at several places in Japan during the year of 1963. Among 10,358 individuals submitted to the test, 24 proved to be hypocatalasemia, i.e., the state of acatalasemic gene carrier. The examinee consisted of five different populations; 1,050 students of Okayama University, 2,363 school-children at Akasaka, Gifu Pref., 598 Korean school-children around Hiroshima City, 2,109 people including school-children at Kozagawa, Wakayama Pref. and 4,238 school-children at Tsushima Is., Nagasaki Pref. The rate of hypocatalasemic cases varied from zero to 0.67% in each place. Concerning acatalasemia, the reported cases amounted to 34 families and 76 individuals by the end of 1963.