Perfusion of the cerebral blood flow in patients with cerebral vascular insufficiency was studied using perfusion computed tomography before and after monotherapy with fraxiparine (single dosage 0,3 ml/2850 ME daily during 20 days) in 20 patients with clinical presentations of this disease in combination with antiphospholipid syndrome and the predominantly distinct hyper production of antiphospholipid antibodies revealed by ELISA. Fraxiparine was administered after the detection of significant changes (not less than 5%) of densitometric parameters characteristic of the state of brain tissue perfusion. Such differences the authors called the signs of «densitometric parameters lateralization» It was shown that the lateralization of X-ray density and its extent, though did not correspond to the severity of clinical presentations of the disease, completely vanished or decreased to the statistically non-significant differences after the treatment. The therapy with fraxiparine significantly increased the blood flow through the brain tissue that was observed in all patients. Thromboprophylactic dosages of fraxiparine improvef the brain microcirculation and reduced the "capillary" hypoxia that correlated with dynamics of neurological disorders specific to the initial signs of chronic brain ischemia.