Objectives:  Childhood obesity has become a worldwide public health concern over the past decade, counting Bosnia and Herzegovina (BiH). The Childhood Obesity Surveillance Initiative (COSI) was established by the World Health Organization (WHO) to address the lack of standardized surveillance data on childhood obesity. However, BiH and its entity, Republic of Srpska (RS), are failing inclusion in such initiative, which hinders efforts to monitor and address the issue. Henceforth, the objective of this nationally funded study was to gather and analyse data on the prevalence of overweight and obesity among primary-school children in RS by implementing the COSI methodology.

Methods: Weight, height, and BMI of first, second, and third grade children (aged 6-8), from 11 schools (N = 2,030) in the RS region was analysed according to the standardized COSI protocol.

Results: The prevalence rates of overall overweight (OW) and obesity (OB) observed were 14.37% (OW 9.09%, OB 5.21%). No gender-related differences were noted (boys 14.36%, girls 14.88%).

Conclusions: These findings highlight a concerning trend of increasing overweight and obesity prevalence with age among primary-school children in the RS.