Background and Aim: Spasticity is a motor disorder characterized by a velocity dependent increase in tonic stretch reflex and tendon jerks, due to the hyper-excitability of the stretch reflex. Modified Tardieu Scale (MTS) is a clinical tool for assessment of spasticity. The purpose of this study was to investigate intra-rater reliability of the MTS for knee extensors and ankle plantar flexors muscles in adult subjects with chronic stroke.

 Materials and Methods: In an analytical cross sectional study, 17 participants (10 men ,7 women) with age range of 40-76 years and mean time post stroke of 20/79 (SD=20/55) in a convenient sampling took part in this test-retest study. Intra-rater reliability of spasticity with MTS was investigated by one un-experienced physiotherapist for knee extensors and ankle plantar flexors in two sessions over one week. 

 Results: Interclass correlation coefficient (ICC) values for R₂-R₁ as an indicator of spasticity in knee extensor and plantar flexors was good (ICC=0/66) and very good (ICC=0/87) and for knee extensors and ankle plantar flexors quality of muscle reaction was 0.80 and 0.92 respectively.

 Conclusion: The MTS has a good reliability in spasticity assessment of knee extensors and ankle plantar muscles after stroke. Probably MTS can be used as a reliable clinical tool to measure spasticity of lower extremity muscles in adult subjects with chronic stroke.