Ten patients with fatty liver, distinct from the well known diffuse alcoholic variety, comprise this report. All patients had an initial ultrasound examination followed by 99mTc-sulfur colloid liver and computed tomography (CT) body scans. Six patients had focal fatty infiltration producing a space-occupying mass within the liver. Four had ultrasound evidence of diffuse fat occurring in association with focal masses. These masses were all echo poor relative to the adjacent fat, and were subsequently found to represent nodules of normal uninvolved liver in two patients, and metastatic neoplasm and multiple liver cysts in single patients respectively. The clinical picture associated with fatty liver is variable and may include, in addition to alcohol abuse, obesity, malnutrition, exogenous glucocorticoids, diabetes mellitus, and other less well defined factors. Dramatic improvement in fatty liver occurred in two patients following appropriate therapy. The spectrum of changes produced by fatty infiltration of the liver on ultrasonic, radionuclide, and CT scans is extremely varied depending on the amount of fat deposition, its focal or generalized nature, and the presence of associated liver disease.