Heinz's Bodies in the erythrocytes floating in the urines and in the body fluids of healthy individuals, and those found in the cases suffered from various diseases were studied. In view of the vicissitudes of Heinz's Body formations in the blood and by means of Yoshida' s method, the following results were obtained. 1. Heinz's Bodies in the microscopic hematuria after the exercises were foiund in 3 out of 32 cases of healthy males and in 3 out of 5 healthy females. No Heinz's Body was found in the circulating blood. The quantity of Heinz's Bodies produced by Yoshida's method was increaced in comparison with the previous reports, but there was no relationship with those in the urine. 2. Heinz's Bodies in the urine were positive in 3 out of 10 acute nephritis cases (3.7%) and so were in one case of valvular heart disease (2%). 3. It was thought that Heinz's Bodies in the hematuria where produced in the tubules by escape and oxydation of catalase in erythrocytes filtered from glomeruli. 4. In one case with the joint exudate, Heinz's Hodies were found at the rate of 2%.