Introduction - The aim of this study was to describe the level of physical activity (PA) among school-aged children in northern France, using an objective measure of PA.Methods - The study included 252 children aged 9.9 ± 0.9 years, with a height and body weight of 1.39 ± 0.08 m and 35.8 ± 8.8 kg, respectively. Their usual PA was assessed over an entire week using an accelerometer. Results - Time spent in moderate-to-vigorous physical activity (MVPA) ranged from 142 ± 44 min/day to 25 ± 18 min/day depending on the threshold used. Boys were significantly more active than girls (p = 0.001). Overweight or obese children spent significantly less time in MVA determined using a threshold of 3,200 cpm (-26%) or 3,600 cpm (-35%) (p<0.01). Between 5% (8% of boys vs. 1% of girls, p<0.0001) and 9% (14% of boys vs. 3% of girls, p<0.0001) of the children met the PA recommendations. Conclusion - This low proportion of active children (<10%), as well as the relatively high proportion of overweight or obese children (>25%), would justify more aggressive physical activity promotion initiatives. These initiatives should target all children in this region regardless of their socioeconomic background. (R.A)