The purpose of this study was to identify sex and age specific differences in fatness and motor fitness levels of children in two western Balkan countries in south-eastern Europe: Slovenia and Serbia. The sample consisted of 1,659 subjects of both sexes, aged from 9 to 15 years. Body height, body mass, triceps skinfold thickness, bent arm hang and standing long jump were used in the analysis. Ordinal regression was used to test differences in body mass index (BMI) categories among the countries. MANOVA was used to test the differences in motor fitness level. There were statistically significant (p<0.001) differences between the countries for the entire set of tested variables. Boys and girls from both countries had similar body height, body mass and BMI, yet Slovenians had smaller triceps skinfold thickness. Children from both countries were superior in standing long jump compared to their counterparts elsewhere in Europe. However, Slovenian boys and girls performed better than Serbian ones in both performed motor tests. Differences between countries in motor tests results were larger at age 9 than at age 14. Apparent trend was detected: with similar morphological characteristics, Slovenian children, especially girls, are physically fitter than Serbian ones. Sex is the only significant parameter (p<0.001) of classifying into a BMI category. Boys have an approximate odds ratio of 1.75 for passing into a higher BMI category as girls. Among girls, the differences between countries were greater since the prevalence of overweight and obese girls in Slovenia decreases with age, while the reverse trend is observed in Serbia.

KEY WORDS: Obesity; Overweight; Body mass index; Physical fitness; Skinfold thickness.