INTRODUCTION: Despite the short-and long-term benefits, the continuous use of orthotics causes impairments due to movement restriction, such as disuse atrophy of ankle plantar flexor muscles. Consequently, an inefficient push-off might be present, generating kinematic compensations in distant regions of the ankle (e.g. pelvis), due to force transmission thru interactions of the body kinetic chain. Thus, the objective of present pilot study is to verify whether there is a difference between conventional polypropylene ankle foot orthosis (AFO) and tridimensional (3D) printing AFO with and without ankle external propulsion system, in pelvis kinematics during the gait of children with cerebral palsy (CP). METHODS: This pilot study investigated the plegic lower limb kinematic data, during self-selected walking speed, of five children with hemiplegic CP (5 to 17 years old) were collected with a 3D motion analysis system. One-way ANOVA repeated measures was used to compared pelvis frontal and transverse plane amplitudes in two hinged AFO on three conditionsconventional, 3D printing with and without propulsion system. RESULTS: Pelvis amplitude in transverse plane showed differences between conditions (p = 0,04), indicating that AFO with propulsion system increases pelvic rotation during gait. That is, more energy might reach pelvis coming from the ankle, through 3D printing AFO with propulsion system, increasing pelvis transverse plane movement, and facilitating the swing of the contralateral limb forward. Pelvis frontal plane amplitude was not significant (p = 0,16). CONCLUSION: Gait analysis demonstrated differences in the transverse plane amplitude of the pelvis, when comparing the three AFO conditions. The assistance of a propulsion system simulating the action of the triceps sural muscle might be able to increase pelvic rotation in the transverse plane, positively impacting gait pattern. Pelvic rotation may influence other gait parameters such as step length and symmetry between limbs, which should be investigated in the future.