Silent stroke is frequently recognized in elderly persons. Diffusion-weighted magnetic resonance imaging has proved to be highly sensitive in the detection of recent silent stroke, and may further applications in the future. Silent stroke in healthy and asymptomatic individuals mainly comprises lacunar infarcts, which are often associated with white matter changes. Thus, analyses of risk factors and genetic factors in small-vessel diseases such as lacunar infarct and white matter changes may provide clues regarding the pathogenesis of silent stroke. Silent stroke may be a risk factor for clinical stroke and cognitive impairment, but prospective studies are required to confirm this.