Objective: To compare the responsiveness of all components of modified Tardieu scale and modified Ashworth scale after botulinum toxin type A intervention in children with spastic cerebral palsy.Design: A randomized controlled trial.Setting: Hospital rehabilitation department.Participants: Thirty children with spastic cerebral palsy.Methods: Participants are randomly assigned to botulinum toxin intervention and physiotherapy group(Group P-B)and physiotherapy group(Group P).One day before and two weeks after botulinum toxin intervention,modified Tardieu scale and modified Ashworth scale are applied to test the spasticity of ankle plantar and elbow flexors.The responsiveness as measured with the two scales is compared with Standardized Response Mean(SRM=average change in Group P-B/SD of change scores in Group P-B)and Guyatts responsiveness index(GRI=average change in Group P-B/SD of change in Group P).Results: When measuring the spasticity of ankle plantar flexors,both modified Tardieu scale(SRM=0.86~7.21,GRI=0.56~4.93)and modified Ashworth scale(SRM=1.11~1.26,GRI=1.52~1.84)showed large responsiveness.When elbow flexors spasticity is assessed,the spasticity angle Y,the fast stretch angle R1 of modified Tardieu scale(SRM=7.21,GRI=7.59~9.8)and modified Ashworth scale(SRM=1.09,GRI=l.59)showed large responsiveness,while the spasticity grade X,the slow stretch angle R2 of modified Tardieu scale showed the small responsiveness(SRM and GRI unavailable).Conclusion: Both modified Tardieu scale and modified Ashworth scale showed large responsiveness in assessing the spasticity of children with spastic cerebral palsy to botulinum toxin treatment.In particular,the fast stretch angle R1 of modified Tardieu scale might be the best component for accessing the spasticity reduction,as it showed the highest value.