Background and Purpose-Associations among microbleeds, white matter lesions (WMLs), and small deep infarcts on imaging have been reported. Because many of these imaging infarcts were as asymptomatic, the relationship of microbleeds to clinical lacunar stroke is unclear. An association between microbleeds and clinically defined lacunar stroke might suggest a common causal microangiopathy. Methods-Patients with lacunar, partial anterior circulation or posterior circulation stroke syndromes and older healthy subjects underwent MRI. Microhemorrhages, infarcts, hemorrhages, and WMLs were coded blind to clinical details. A final clinicoradiologic stroke subtype diagnosis was assigned. Results-Among 308 subjects (67 older healthy and 241 with stroke), 54 patients had microbleeds (17%). Microbleeds were twice as frequent in lacunar than cortical strokes (26% versus 13%, P=0.03) or healthy older subjects (9%) and associated with increasing WML scores (P < 0.0001). Lacunar and cortical stroke subtypes and healthy older subjects had similar WML scores. Conclusions-Microbleeds are associated with lacunar stroke defined clinicoradiologically more than other stroke subtypes but not simply by association with WMLs. This suggests that microbleeds and lacunar stroke have a similar microvascular abnormality.