The blood coagulation system has been shown to be activated in subacute exacerbations of Binswanger disease (BD). In our previous study, the antithrombin drug argatroban ameliorated the neurological exacerbations in a BDpatient with antiphospholipid antibody syndrome. We have further examined the therapeutic efficacy of argatroban in 3 BDpatients with subacute exacerbations, but without any immune-mediated prothrombotic complications. In 1 out of these 4 patients, treatment with sodium ozagrel, an antiplatelet drug was applied, but was ineffective. In all patients, argatroban treatment reduced the levels of the hemostatic markers, with a corresponding improvement in cognitive dysfunction and gait disorders. These results suggest that the antithrombin effect is true also for BDpatients not compromised by the immune-mediated prothrombotic condition. (Internal Medicine 39: 966-969, 2000)