Objectives and background: The main aim of this research was to determine the impact of COVID-19 pandemic on obesity and risk for developing obesity in children who enrolled in primary school during the first three pandemic years (2020. – 2022.). Secondary objectives were to examine the potential differences with regard to gender, to study the potential influence of parental educational level on children’s weight as well as the influence of the number of children in the family on frequency of risk for developing obesity as well as obesity itself and to study whether there is a correlation between body mass index (BMI) of children and their birth weight and length. Patients and methods: This study analised data obtained from the health records of 639 children who were enrolled in the primary school in the area of Trogir in period from 2020. to 2022. Information was collected on the weight and height of children and birth length and birth weight, the total number of children in their families and the parental educational level. The nutritional state was assesed using Croatian national reference values by geneder and age and by using the World Health Organization (WHO) reference curves by gender and age. Results: Obesity was observed in 4.69% of children according to the Croatian reference values. or 9.86% according to the WHO reference values. Excess body weight was recorded in 10.02% of children by the national reference values, or 20.97% by the WHO values. No significant difference in BMI was recorded during the COVID-19 pandemic compared to the pre-pandemic period. No statistically significant differences were found in frequency of obesity or in the frequency of excessive body weight with regard to gender. The level of education of parents did not have a significant impact on BMI during the pandemic, but an increase in the frequency of excess body weight was observed in children whose parents have high level of education compared to the pre-pandemic period. The number of children in the family did not show statistically significant influence on the children’s BMI. Birth weight showed a statistically significant influence on the development of obesty in children. Conclusions: The frequencies of obesity and excess body weight in this study are approximately the same as they were before the pandemic. Parental educational level and the number of children in the family do not have a statistically significant influence on obesity in children during the pandemic. Birth weight significantly affects the development of obesity in children.