1) In 184 cases of healthy persons, patients ailing some diseases and nurses, fibrinolytic activity of the urine was seminquantitatively measured according to the method which was first reported by Unger & Mist and applied to urine by Colgan et al. The criterion of judgement of the results was also based upon that of Colgan et al.
2) Fibrinolytic activity of the urine was found higher than normal in 19 cases of pregnancy out of 27 (70%), and in 12 out of 19 cases of nurses who received a small amount of irradiation (63%). Fibrinolytic activity of blood, however, remained normal in the most of those cases.
3) Fibrinolytic activity of urine was found normal in 50 cases of aplastic anemia out of 51 and in 24 out of 27 cases of leucemia and erythroleucemia. Fibrinolytic activity of blood in most of these patients was found to be higher than normal.
4) In 8 cases of malignant tumor out of 27, fibrinolytic activity of the urine was higher than normal. In about half of such patients, fibrinolytic activity of blood was found also to be higher than normal.
5) These accelerated fibrinolytic activity of the urine samples turned normal when ε-amino-n-caproic acid was added to the reaction mixture in vitro.