We compared possible factors leading to symptomatic and asymptomatic reinfarcts in 207 patients an average of 2.1 years after their index athero-thrombotic stroke presenting with small subcortical infarcts. Symptomatic reinfarcts were mostly small infarcts in the perforating artery regions associated with angiographic evidence of atherosclerosis of parent arteries (large-artery disease), a high hematocrit, elevated fibrinogen and Lp(a) levels. They occurred with insufficient inhibition of platelet aggregability in patients receiving antiplatelet medication. In contrast, many asymptomatic reinfarcts were small perforator infarcts not associated with large-artery disease or cortical infarcts, and occurred in the absence of hematologic risk markers, and in spite of sufficient inhibition of platelet aggregability.