Mammography is the preferred technique to evaluate the breast but computed tomography (CT) performed for extramammary disease often images breast tissue. We reviewed studies of patients who underwent both CT and mammography to identify abnormalities that were visible with both techniques. The CT appearance of the normal breast, breast cancer, and several other abnormalities is demonstrated in this study. CT may occasionally allow for a precise diagnosis of a previously unsuspected breast lesion but a mammogram is usually required.