We report presumed mechanisms of recurrent stroke in a prospective study on patients with lacunar infarction. Eighty-one patients with clinical and magnetic resonance imaging (MRI) findings compatible with lacunar infarction were followed for a median time of 48 months. Patients with recurrent stroke were assessed clinically by computed tomography, contrast-enhanced MRI and with respect to large-artery disease and cardioembolic sources of embolism. During follow-up, 9 patients (11.1%) died and 20 patients (24.7%) had 27 recurrent strokes (3 hemorrhagic, 24 ischemic). The annual risk of recurrent stroke was 6.8% and approximately even with time. Univariate analysis revealed age as the only risk factor significantly associated with recurrent stroke. Out of 24 episodes of recurrent ischemic stroke, 16 had clinical and neuroimaging features compatible with small penetrating artery occlusion, 6 were due to cortical infarcts, 1 episode was caused by presumed cerebral amyloid angiopathy, and 1 by a retinal infarct. Relevant large-artery disease was diagnosed in 2 patients with recurrent, small brainstem infarcts and in 2 patients with recurrent cortical and retinal infarcts. Although presumed lacunar infarcts predominated, our series highlights the heterogeneity of recurrent strokes after lacunar infarcts.