The aim of this study was to investigate whether the modified Tardieu scale (MTS) in a semi-standing position, used for the assessment of hamstrings spasticity, was better associated with knee extension and hamstrings activity in terminal swing than the MTS in a supine position in children with cerebral palsy (CP). Seven children diagnosed with spastic CP (Gross Motor Function Classification System Levels I-II) and seven healthy comparison children participated in the study. An instrumented MTS in supine and semi-standing position and an instrumented gait assessment were conducted. Results showed that spasticity-related outcomes of the semi-standing MTS do not show better associations with terminal swing characteristics of gait than the same outcomes of the supine MTS in children with spastic CP. Only the passive restricted knee angle from the supine MTS was strongly associated with the maximum knee extension during gait (r[subscript s]=0.99; p less than 0.001), suggesting that hamstrings length is more important for terminal swing behaviour than hamstrings spasticity.