The Somatomorphic Matrix (SM) is a computer-based body image assessment program that allows assessment of the individual's body image in relation to known body composition values. To date, no study has compared the SM results to the measured body composition and assessed the usefulness in multi-ethnic samples. Japanese and Australian Caucasian males underwent testing to examine the SM body image results to their measured body composition. Japanese males showed significant (p<0.01) discrepancy in their measured and the perceived 'current' muscularity compared with Australians. Both groups showed wide variability in the perception of their 'current' body composition in relation to the measured values, indicating an incomparability of the SM results to the measured results. The study also showed Japanese males to have lower consistency in the SM results than Australian males after a 12-month interval. In order to use the program in multi-ethnic populations further development of the program is recommended.