The aim of this investigation is to assess modifications in sway parameters introduced by backpack carriage in Italian primary school children (6-10 years old, n = 447). Two 30-s trials (without and with backpack) were performed directly at a school on a regular school day to collect data on sway area, centre of pressure path length and maximum displacement range in antero-posterior and medio-lateral directions. The results show a significant load-induced increase in all sway parameters and the existence of a linear relationship between sway area and backpack weight. Since postural sway represents an effective indicator of balance abilities, the alterations observed suggest that backpack carriage originates balance impairment and thus may increase the risk of unintentional falls in children. STATEMENT OF RELEVANCE: Loss of balance is among the primary causes of unintentional falls and postural sway represents an effective indicator of balance abilities. In this study, sway parameters were assessed in primary school children wearing backpacks. The differences that were observed show that backpack carriage potentially increases the risk of falls.