Liver volume was measured by computed tomography in 54 children and young adults with no history of liver disease. Their ages ranged from 10 days to 22 years. The volume was calculated as follows: (1) the edges of the liver were traced on each scan image and the area was calculated by computer; (2) the areas were summed and multiplied by the scan interval in centimeters. The mean liver volume (+/-SD) was 178.2 +/- 81.9 cm3 in infants (less than 12 months old) and 1114.3 +/- 192.9 cm3 in adolescents (more than 16 years old). The mean liver volume in relation to body weight (+/-SD) was 34.1 +/- 5.5 cm3/kg in infants and 20.2 +/- 3.1 cm3/kg in adolescents. In general, liver volume increases rapidly in infants, gradually in schoolchildren, and not at all in adolescents. Volumetry might be clinically useful for evaluating the liver function in children and determining the graft size in liver transplantation.