We developed a method for calculating adipose-tissue areas from transverse body scans by magnetic-resonance imaging (MRI). The method is based on an inversion recovery experiment (repetition time 820 ms, inversion delay time 300 ms, and echo time 20 ms). Total-fat areas and subcutaneous-fat areas were calculated by this method and by computed tomography (CT) from abdominal scans taken in seven male volunteers. The SEE ranged from 4.4 cm2 (CV 4.4%) for subcutaneous-fat areas to 8.3 cm2 (CV 12.8%) for visceral-fat areas. The reproducibility of measuring fat areas with MRI was assessed in seven other volunteers (four males, three females). The average errors of the method for different fat areas were 5.4%, 10.6%, and 10.1% for total-, visceral-, and subcutaneous-fat areas, respectively. We conclude that CT and MRI may yield different absolute values of fat areas (especially visceral fat) but that the ranking of individuals on the basis of their fat areas will be similar by both methods.