The main purpose of this study was to investigate fine motor control in obese and overweight children compared to normal-weight peers under different postural constraints. Peg placing performance of normal-weight (n=273), overweight (n=202) and obese (n=65) children (aged 5.0-12.8 years) was evaluated in two different postural conditions: sitting and standing in tandem stance on a balance beam (BB). Being overweight or obese was detrimental for fine motor skill performance in the standing on BB condition, which confirms the postural control difficulties observed in overweight and obese children. Remarkably, obese participants also produced lower scores in the sitting condition, i.e. when the complexity of postural organization was restricted to a minimum. Although this could result from the mechanical demands related to the movement of the arm itself, it also leads to the tentative suggestion that obese children might suffer from underlying perceptual-motor coordination difficulties.