In this report the diffusion-weighted imaging (DWI) findings and ADC values of leukoaraiosis (LA) and associated periventricular ischemic lesions were assessed. Seventy-eight patients with LA were examined with magnetic resonance imaging (MRI) and DWI. Twenty one patients (28%) were found to have focal acute white matter infarction on DWI which could not be detected and discriminated on the basis of MRI findings alone. LA and acute white matter infarction both showed hyperintensity on standard T2W MRI, whereas acute infarction revealed focal hyperintensity on DWI. Thirteen patients (16%) had chronic lacunar infarctions in the white matter. ADC values of LA, acute and chronic white matter infarctions were calculated and found to be significantly different from each other (p<0.05). It is concluded that DWI is necessary in the detection of acute periventricular white matter infarction from LA.