The computed tomographic features in 14 children (age range = 2 days to 10 years) with cystic hygromas of the neck and lymphangiomas of the chest, abdomen, and extremities were studied. Computed tomography can determine the morphology of these masses, their exact locations and their relationship to other organs. Most lymphangiomas appear as cystic masses of low attenuation value with or without septations. The septations may be thin or thick and result in a conglomerate of cysts of irregular borders, varying in size from a few millimeters to several centimeters. Some of the septae show enhancement after a bolus injection of contrast material. Contrary to what has been reported, lymphangiomas may invade nearby tissues and organs.