Imaging studies of the liver and spleen are most commonly performed with 99m Tc sulfur colloid. Radio-iodinated rose bengal and chromium-51 heat damaged red blood cells are, respectively, liver and spleen specific and, therefore, provide a confirmatory examination if there is any confusion or problem in interpretation of the colloid study. Because of its efficiency and positioning versatility, the gamma camera is the instrument of choice for these studies in children. Congenital abnormalities are easily demonstrated. Space-occupying lesions such as tumors, cysts, and abscesses appear as focal defects, whereas homogenous involvements such as infections, cirrhosis, storage diseases, and leukemia cause a diffuse reduction in hepatic activity concentration, as well as increased uptake in the spleen and vertebral marrow. Extrinsic pressure defects from neighboring structures such as the gallbladder, kidney, and diaphragm are often indistinguishable from intrahepatic lesions. Technical modifications of the Anger camera facilitate dynamic studies which may be superimposed on static images, e.g., inferior vena cava over liver and combined organ examinations, e.g., lung and liver.