Purpose : The purpose of this study was to compare the clinical utility of diffusion-weighted images(DWI) with that of apparent diffusion coefficient(ADC) maps for detecting early ishemic strokes. Materials and Methods : In 22 patients with infarct, lesion conspicuity as seen on T2-weighted images(T2WI), low diffusion-weighted images(DWI ; b value 300 sec/$ extrm{mm}^2$), high DWI(b value 1000 sec/$ extrm{mm}^2$), and ADC maps was retrospectively compared. The infarct was hyperacute (< 6 hours) in six, acute (< 48 hours) in six, and subacute (< 2 weeks) in ten. All images were obtained using an echo-planar spin echo sequence; lesion conspicuity was graded from 0 to 2 by two radiologists. Signal intensity was analysed in 17 patients[hyperacute (n=5); acute (n=4); and subacute (n=8)].Lesion-to-controlateral normal side signal intensity ratio(SIR) and contrast-to-noise ratio(CNR) were measured and compared between four different types of images. Results : With regard to lesion conspicuity, high DWI was superior to the other images for detecting hyperacute strokes(Grade 2, 6/6). In such cases, an ADC map showed grade 0 lesion conspicuity in one case, grade 1 in three, and grade 2 in two. There was no significant difference in lesion conspicuity in acute and subacute strokes between DWI(low & high) and T2WI(Grade 2, 16 in each). An ADC map in acute and subacute stroke showed Grade 1 in four cases and Grade 2 in 12. Signal intensity analysis of SIR and CNR showed that high DWI was also superior to the other images for detecting hyperacute ischemic strokes(p <0.05, n=5), and superior to an ADC map in acute and subacute stroke(p < 0.05, n=12). Conclusion :Diffusion-weighted images with a high b value could be more useful than ADC maps and conventional T2-weighted images, especially for the detection of hyperacute strokes.