The aim of this study was to quantitatively assess the stability and harmony of gait in children with cerebral palsy. Seventeen children with spastic hemiplegia due to cerebral palsy (5.0 [plus or minus] 2.3 years old) who were able to walk autonomously and seventeen age-matched children with typical development (5.7 [plus or minus] 2.5 years old, p = 0.391) performed a 10-m walking test with a wearable device fixed to their lower trunk and included a triaxial accelerometer and three gyroscopes. Three parameters related to gait stability and three related to gait harmony were computed; all of these yielded significant differences between children with cerebral palsy and those with typical development (p less than 0.020 for all the computed parameters). In the latter group of children, trunk accelerations were found to be negatively correlated with age (partial correlation controlled for walking speed: R[subscript P] less than -0.58, p greater than 0.020). Conversely, in children with cerebral palsy, the upper body accelerations were proportionally correlated with their gait speed (R = 0.548, p = 0.023 in the antero-posterior direction) but not with their age (p greater than 0.05). This finding can be related both to difficulties in managing the higher upper body accelerations involved in rapid walking and to compensation strategies. (Contains 2 figures and 2 tables.)