We correlated coagulation and fibrinolytic parameters with small-vessel disease revealed by magnetic resonance imaging (MRI) of the brain. One hundred and eleven patients with asymptomatic or symptomatic cerebral infarction were randomly selected for the study; 57 males and 54 females with an average age of 66.6 +/- 9.6, age range 40 to 85, years old. Among them, 76 patients had a history of symptomatic cerebral infarction; 38 patients hypertension; and 24 patients diabetes mellitus. Patients with large cortical infarction, cerebral hemorrhage, demyelinating disease or mass lesions were excluded from the present study. The MRI scans were reviewed for areas with increased signal intensity on T2-weighted images. The small infarction was defined as a lesion less than 10mm in diameter. The activity of von Willebrand factor (vWF) correlated significantly with the grade of caps at the anterior and posterior horns of the lateral ventricle, and the number of small infarctions in the subcortical white matter and basal ganglia, suggesting vWF could be a predictor for these small-vessel disease. The grade of caps at posterior horn of the lateral ventricle and the number of small infarctions in the subcortical white matter were associated significantly with the concentration of plasma fibrinogen and reversely with the activity of antithrombin III, an inhibitory factor in coagulation system. These results indicate that hypercoagulable state may causatively relate with small-vessel disease in the territory of medullary artery branching from cortical artery. On the contrary, these coagulation parameters did not correlate significantly with small ischemic lesions in the territory of perforating artery. No correlation was observed between the level of marker proteins for platelet activation and the degree of small-vessel disease, indicating the activation of platelet could not associate with the etiology of small-vessel disease.