Positron emission tomography (PET) has opened new fields of investigation on clinicometabolic correlations in subcortical infarcts. Functional changes occurring in structurally unaffected brain regions represent one of the most interesting aspects of PET application. So far, the only one PET study on lacunar infarcts has not shown any significant cortical metabolic abnormality. Correlations between distribution and severity of cortical metabolic depression, the size and site of lesion and clinical symptoms still have to be better elucidated.