PURPOSE: To determine if Pilates-based exercise classes could be feasible and effective in changing gait kinematics and balance in ambulant children with Cerebral Palsy (CP). MATERIALS AND METHODS: A single-blind multi-centre randomised controlled trial compared a four-week, twice-weekly Pilates-based exercise class to a usual exercise control, for ambulant children with CP. Clinical outcome measures were three-dimensional trunk and lower limb kinematics during walking on level ground, uneven ground and crossing an obstacle; and clinical balance measures. Feasibility outcomes were adherence and enjoyment. RESULTS: Forty-six children (29 male, mean age 10 years 8 months (range 7-17 years), 23 per group) participated. After the four-week intervention, there were no significant between-group differences in trunk or lower limb gait kinematics. Differences were detected in Berg Balance Scale (1.38 points, 95% CI 0.58-2.18) and Functional Walking Test (1.40 points, 95% CI 0.58-2.22), but they were less than the minimum clinically important difference and therefore clinically insignificant. Median class attendance was 5/8 classes. CONCLUSION: Pilates-based exercises did not change lower limb or trunk kinematics during walking in children with CP and had a clinically insignificant impact on balance. Lower than anticipated adherence prompts consideration of more flexible delivery of future interventions. Implications for RehabilitationAmbulant children with CP can experience impairment of trunk control, negatively impacting balance and gait.In this study, Pilates-based exercise classes did not change kinematics of the trunk or lower limbs during walking and led to negligible improvement in functional balance.Children did not manage to do their Home Exercise Programme, indicating that Pilates-based exercise should be delivered within supervised practice.Children missed on average one in three classes due to unforeseen circumstances, so this should be anticipated when planning group classes.