Introduction: Motor skill development during primary school years lays the foundation for children's active participation in physical activities and a healthy lifestyle. Given the increasing prevalence of obesity during this period and its potential impact on movement patterns, investigating the relationship between weight status and motor proficiency is of particular importance. Therefore, the present study aimed to compare the motor proficiency of primary school children with normal, overweight, and obese body mass index (BMI) classifications.

Methods: In this causal-comparative study, 380 children (boys and girls) aged 8–12 years from Najafabad, Iran, were selected through convenience sampling. Weight classification was performed using BMI percentiles for age and sex, according to the 2000 CDC/NCHS guidelines. Motor proficiency was assessed using the short form of the Bruininks-Oseretsky Test of Motor Proficiency. Data were analyzed using one-way ANOVA, Tukey's post-hoc test, and Pearson correlation coefficient.

Results: The results showed significant differences in motor proficiency among children with obesity (44.4 ± 6.2), overweight (41.6 ± 7.6), and normal weight (45.7 ± 6.8). Motor proficiency in both normal-weight and obese children was significantly higher than that in overweight children; however, no significant difference was found between normal-weight and obese children. Additionally, positive and significant correlations were observed between motor proficiency and BMI in both normal-weight and obese children.

Conclusion: Based on the findings of this study, which indicate differences and associations between obesity and motor proficiency, it is recommended that specialists consider children's weight when implementing motor skills programs.