An advanced screening method of hypocatalasemia was designd, using (1) perborate as substrate (perborate method) which is stabler and easier to prepare than hydrogen peroxide (H(2)O(2)) as substrate (H(2)O(2) method), and (2) an experimental device which makes the reaction procedure semi-automatic. The following results were obtained; 1. Regression equation was established between the catalase activities measured by perborate method and those of H(2)O(2) method. 2. Discriminant point was calculated from this equation with the discriminant value by H(2)O(2) method established by Ogata et al. The volume of potassium permanganate to be added for the final discrimination, thereby, was calculated. 3. The reaction procedure could be made semi-automatic by an experimental device which consists of a circulating water-bath and a rotary type fraction collecter. Eighteen specimens could be examined in about 10 minutes. 4. In borderline cases quantitative analysis is immediately available with this device.