The aim of the study was to identify differences between trained and untrained subjects with respect to body composition and motor abilities. Two groups of subjects participated in the study: young judoists (110 boys and 56 girls) and their untrained mates (115 boys and 60 girls), aged 11 to 16 years, all from the Province of Vojvodina, Serbia. Young male judoists proved significantly better than their untrained mates in repetitive and static strength exercises, running speed, whole-body coordination, and had lower subcutaneous fat tissue of the upper arm. Young female judoists were significantly better in repetitive strength, whole-body coordination and plate tapping, chest girth and stretched upper arm, and also had lower subcutaneous fat tissue of the upper arm and back.