Cerebral palsy (CP) is a neurological disease due to brain damage and it is the leading cause of pathological gaits in childhood. The Gross Motor Function Classification System (GMFCS) is commonly used to classify the degree of motor impairments (5 levels) together with their anatomical distribution (unilateral or bilateral CP) and type (spastic, ataxic or dyskinetic CP) (Rosenbaum 2003). Comorbidities like intellectual, visual and hearing disabilities usually co-exist with CP (De-Luca et al. 2012). Several authors already studied the effects of the CP on the kinematics and the dynamics parameters of the musculo-skeletal system during gait. The GMFCS was demonstrated to be highly correlated with the profile and the authors always observed a decrease in the Range of Motion (ROM) of the joints compared to healthy subjects. This abnormal pattern locomotion could lead to increase energy consumption, gait instability and fatigue (Eek et al. 2017). With the final aim of building an exoskeleton for rehabilitation purposes, we present for the first time a kinematic comparison of 2 true twins, one healthy and one with a cerebral palsy diagnosis to better understand the corrections which must be applied to recover a healthy gait. Our hypothesis is that the healthy child is the reference to be mimic by the CP child.