The aim of this study was to evaluate the differences in cerebral perfusion seen on mean transit time (MTT) and cerebral blood volume (CBV) maps and to assess the subsequent prognostic value of the MTT-DWI (diffusion-weighted MRI) and CBV-DWI mismatch in the first three days of stroke on lesion enlargement and clinical outcome. In 38 patients, imaged 1-46 h after onset of symptoms, lesion volumes on proton-density (PD)-weighted MRI, DWI and PWI (both MTT and CBV maps) were compared with lesion volumes on follow-up PD-weighted scans, and to clinical outcome (National Institutes of Health Stroke Scale, Barthel index, and Rankin scale). The MTT-CBV, MTT-DWI and CBV-DWI mismatches were compared with change in lesion volume between initial and follow-up PD-weighted scans. Lesion volume on both DWI and PWI correlated significantly with clinical outcome parameters (p < 0.001) with strongest correlation for lesion volume on CBV. Perfusion-diffusion mismatches were found for both CBV and MTT and correlated significantly with lesion enlargement on PDweighted imaging with strongest correlation for the CBV-DWI mismatch. The CBV-DWI mismatch has the highest accuracy in predicting lesion size on follow-up imaging and in predicting clinical outcome. Lesion volume measurements on CBV maps have a higher specificity than on PD-weighted, MTT or DWI images in predicting clinical follow-up imaging and in predicting clinical outcome.