From the analysis of information on 158 patients who underwent operation for aneurysm of the abdominal aorta and on the basis of complications associated with impaired hemostasis, considerable disorders were revealed in the blood rheologic and coagulative properties. These disorders intensify during the operation and in the first 3 postoperative days and may lead to the development of microcirculatory and thrombotic complications. The syndrome of generalized intravascular coagulation may develop in patients with large aneurysms of the abdominal aorta, in which operations are most traumatizing. A scheme for correcting disturbances in the blood rheologic and coagulative properties in the pathological condition is given.