Measurements were performed on commercial broiler chickens by magnetic resonance imaging (MRI) tomography. A total of 72 chickens were scanned at the age of 6, 7, 8, 10, 16 and 20 weeks. MRI scans based on spin echo sequence were taken in the three orthogonal planes. The volume of the pectoral muscles increased from 259 cm3 to 1035 cm3 in males and from 250 cm3 to 875 cm3 in females between 6 and 20 weeks of age. Abdominal fat volume increased from 18.9 cm3 to 153.2 cm3 in males and from 19.3 cm3 to 267.0 cm3 in females between 7 and 20 weeks of age. Total body fat volume increased from 129 cm3 to 557 cm3 in males and from 171 cm3 to 1321 cm3 in females between 6 and 20 weeks of age. The correlation coefficients between the total volume of fat pixels and the amount of abdominal fat determined in the coronal plane by MRI were 0.85 and 0.95 in the male and female sex, respectively. Changes found in the pectoral muscles (mm. pectorales) as well as in total and abdominal fat volume were in close agreement with dissection data obtained at the slaughterhouse and with laboratory data based on the measurement of total body chemical composition in both sexes. This MRI method can be a good complement to computed tomography (CT) scanning in the transversal plane.