Introduction. The modern world of electronic devices offers children and young people various forms of leisure activities, while reducing the need for natural movement, necessary for normal psychomotor development. Sedentary life contributes to an increased body weight and, thereby, to the development of body posture abnormalities. The aim of the study was to evaluate body posture, leisure activities, and the number of hours spent using electronic devices among children with obesity. Material and Methods. The study involved 51 children with obesity (BMI above 95 percentile) – A group, and 69 children with normal body weight at the age of 9–13 years (10.98 ± 1.29) – B group (control). Body posture has been evaluated with the scoliometer, the digital inclinometer and the plumb line. The hump ratio has been calculated on the basis of SOSORT recommendations. Time spent in front of electronic devices based on a questionnaire results has also been calculated. Results. Children with obesity have more body posture defects in the sagittal plane than children with normal z-scores (p<0.001). 46.8% of children in group A have distorted depth of the two curvatures of the spine. In the control group, the majority of deviations have been observed in the evaluation of the ATR (Angle Trunk Rotation) at the lumbar spine (p<0.05), while in group A, at the level of the thoracic spine (40.42% vs. 23.07%). Both groups of respondents use electronic devices at least 3 days a week (p>0.05). Obese children often use mobile devices, while children with normal body weight often use desktop equipment. Conclusions. Definitely more body posture abnormalities are found in the group of obese children. Children use electronic devices regardless of weight. It is worth to expand educational activities with programs that improve the quality of body posture through a daily change of abnormal patterns.