Silent brain infarctions are frequently found by modern cerebral imaging. Up to 30% of persons without a clinical history of stroke were found to have silent brain infarction in epidemiological studies. "Silent" refers to ischemic brain lesions for which no matching clinical syndrome can be found based on history or clinical investigation. Age, education, and ethnic background have a strong impact on noticing and reporting stroke symptoms. The current clinical definition of stroke is insensitive for cognitive deficits which can also be caused by brain infarctions. The majority of silent brain infarctions are localized in the subcortical white matter of the brain; however, about 10% of silent brain infarctions are cortical. Silent brain infarctions are strongly associated with stroke risk factors and comorbidities that are known to cause clinically overt stroke. Silent brain infarctions are 5 to 10 times more frequent than clinically overt strokes. Silent brain infarctions as defined by DWI lesions on MRI imaging are a frequent finding during operative or interventional procedures and their monitoring may help improve the respective techniques in order to decrease the risk of periprocedural stroke.