This paper introduces a method to detect white matter lesions in brain automatically. Our method tries to determine the regions of lesions unsupervisedly on magnetic resonance (AM) images of a group of patient by using image processing techniques. As a first step, skull is removed from brain tissue using watershed transform and morphological operations. After skull-stripping, seed points selected by using fuzzy, c-means clustering (FCM) algorithm are used in region-growing method. This operation generates the binary mask containing the regions of lesions.