With the master’s thesis I wanted to explore (i) whether motor skills and executive functions (EF) of normal-weight children are correlated and (ii) how do motor skills and EF of three groups of children regarding their body mass index or BMI – normal-weight, overweight and obese – differ. I studied 203 primary school fifth-graders (average age: 10 years and 8 months) from Savinja statistical region in Slovenia. Anthropometric and motor skills measurements were performed by their sport teachers during yearly SLOfit (Sports Educational Chart) routine and testing of EF was carried out with the newly developed Test battery for measuring executive functions; headmasters’ and parents’ informed consent was acquired beforehand. Factor analysis was executed on EF data and Pearson correlation coefficients calculated for correlations between the motor skills and EF; ANOVA with post-hoc tests was used to assess the differences between the groups of children. Results showed that inhibition, flexibility, visual search and verbal fluency were moderately correlated (p < 0,001) with overall motor performance; those EFs were also equally strongly correlated with both aspects of fitness (health-related and physical efficiency-related). Working memory showed no significant correlations with motoric index or two fitness components, but was weakly correlated (p < 0,05) with specific motor skill aerobic endurance. On all the motor skills tasks – except on the Hand-tapping and Stand and reach – normal-weight children achieved the best results and obese children the worst, whereas on the EF tests there were no differences between the groups. One of the study’s main limitations would be the fact that the test battery for EF is not yet validated. Apart from that, it would most probably be useful to test for differences in skills based on sex and whether sex has some impact on the differences between the groups regarding BMI. The important contribution of the research is in its interdisciplinary nature and in the inclusion of EF as the most indirect possible indicator of cognitive skills as opposed to the frequently studied, but direct one – academic achievement.