The objectives of this review are to present various entities that can result in hypointensity on brain T2*-weighted gradient-echo (GE) images and to show the usefulness of this sequence. There are six etiologies, resulting in hypointensity on T2*-weighted GE images, ie, the presence of hemosiderin, deoxyhemogrobin, ferritin, calcium, other metals, and air. This sequence is sensitive to magnetic susceptibility effect and useful for detecting some kinds of small brain lesions and for differential diagnosis in some special conditions.