BACKGROUND: Leukoaraiosis (LA) may have specific clinical correlates in patients with stroke, but this is not well investigated, so that the significance of LA in patients with stroke remains unclear. METHODS: In a study of 2289 patients with a first-ever acute ischemic stroke, LA was noted in 149 by the use of baseline computed tomography of the brain. These patients were compared with the non-LA group. Statistical tests, including Fisher exact test or a chi(2) test, were used to compare variables, and a multivariate approach using stepwise logistic regression was performed. RESULTS: Patients with LA were significantly older (73.7 vs 62.7 years; P<. 001), and had a higher incidence of hypertension (72.5% vs 47.1%; P<. 001) and subcortical or lacunar infarction (40.3% vs 25.4% and 21.5% vs 8.0%, respectively; P<.001) on neuroimaging studies, compared with the non-LA group. The most common cause of stroke in the LA group was presumed to be small-artery disease associated with hypertension (46% vs 13.5% in the non-LA group). Age and hypertension were very strongly associated with LA (respective odds ratios [95% confidence intervals], 1.06 [1.04-1.08] and 2.33 [1.60-3. 39]). In addition to these risk factors, a close relationship was found between LA and nonsevere stenosis (<50%) of the internal carotid artery (odds ratio, 2.23 [95% confidence interval, 1.32-3. 76]), although the significance of this association remains speculative. The outcome at 1 month after stroke was similar in both groups. CONCLUSION: Our results provide further evidence that LA is related primarily to small-vessel disease.