['The pulsatility index (PI), measured by transcranial Doppler (TCD), is a surrogate marker for distal vascular resistance in cerebral arteries, and elevated plasma total homocysteine (tHcyt) is regarded as a cause of ischemic stroke, including lacunar infarction. We investigated the relationship between the PI of cerebral arteries and plasma tHcyt in patients with lacunar infarction.', 'Plasma tHcyt level and TCD examination were performed in 94 patients with lacunar infarction. Mean flow velocity (MFV) and PI were assessed at the ipsilateral middle cerebral artery (MCA) and contralateral MCA, relative to the infarction, and the basilar artery (BA). Multivariate regression analysis was conducted between log-transformed tHcyt levels (logHcyt) and the PI of individual arteries.', 'There was a significant correlation between logHcyt and the PI in all tested arteries (ipsilateral MCA: r=0.21, p=0.03; contralateral MCA: r=0.21, p=0.04; BA: r=0.35, p=0.01). In multivariate regression analysis, this significance remained unchanged after adjusting for vascular risk factors, creatinine, hematocrit and platelet count (ipsilateral MCA: β=0.26, p=0.01; contralateral MCA: β=0.21, p=0.04; BA: β=0.39, p=0.001). There was no significant association between logHcyt and MFV of individual arteries.'] Is plasma total homocysteine level associated with the pulsatility index of cerebral arteries in lacunar infarction?