We reviewed the investigation of liver masses in 45 children. Plain films of the abdomen (in 42) and radionuclide liver and spleen scans (in 38) were nonspecific, although the latter had a sensitivity of 100%. Sonography detected lesions in 39 of the 40 patients in whom it was performed (sensitivity 97.5%), and suggested a specific diagnosis in 16 (41%). Computerized tomography (CT) detected all lesions (sensitivity 100%) and gave more information than the other modalities in 17 of the 38 cases (44.7%), as well as the best definition of the extent of liver lesions. Sonography should be the initial modality of choice in children with suspected liver masses but, in most patients, CT is the single most helpful method for defining the extent of such masses. In addition, CT may also show extrahepatic disease. In a particular clinical context, the characteristic CT pattern of contrast enhancement is diagnostic of hemangioma. Angiography provides a preoperative map of abdominal vasculature in patients with malignant disease or vascular aneurysm, and is indicated for this purpose.