Diffusion MR imaging is now a routine component of the brain MR imaging examination and is critical in the evaluation of stroke patients. However, high signal intensity on diffusion MR and hypo intensity on apparent diffusion co-efficient (ADC) images, which are features of acute cerebral infarction, have been reported in such diverse conditions as hemorrhage, abscess, tumor and even in Wernicke encephalopathy. Differentiating between there conditions is critical for determination of appropriate treatment. We present a systematic review of hyperintense lesions on diffusion MR images and their potential clinical applications.