[en] From the atomic bomb survivors who visited Hiroshima Atomic Bomb Hospital for a complaint of hemorrhagic diathesis, 15 patients who were required hospitalization were chosen for an evaluation of the hemorrhagic diathesis. 11 cases of them had vascular disorder and 4 thrombocyte abnormality, and there was no case of coagulation abnormality which may cause hemorrhage. A case of purpura angiopathica recently died from encephalomalacia, and its autopsy disclosed amiloidosis. This is very interesting because amiloidosis is a disease which systematically damages the blood vessels. Case I (in the case report) which had no serious morbid change except for cerebral and subarachnoid hemorrhage and had repeated episodes of extensive subcutaneous hemorrhage. Case 2 which was exposed 1.6 km apart from the epicenter at the age of 3 showed a gradual decrease of thrombocyte count from 210,000 to 40,000 during the course of 3 year, and died from cerebral hemorrhage at the age of 27. There still remain some doubt about the cause of this death. As this survey was done retrospectively, it was difficult to give an acurate diagnosis to each case. However, this result will suggest a general tendency of hemorrhagic diathesis in atomic bomb survivors. (Ueda, J.)