Computer tomography and nephroangiography were performed in 5 patients with angiomyolipoma of the kidneys. CT was characteristic in all cases by demonstrating areas of fat in the tumor, and the extent of the neoplasm could be assessed preoperatively. Nephroangiography was of value as a preoperative demonstration of the vascular anatomy. In one case with a hemorrhage which nearly masked the fat component at CT, angiography added diagnostic information.