Physical activity is suggested to be beneficial for most children with cerebral palsy, whereas studies based on scientific results from reproducibility remain poorly known in such children. This study then asses the reproducibility of skeletal muscle function in children with spastic hemiplegic cerebral palsy, with a control able-bodied children. 16 children with cerebral palsy (Gross Motor Function Classification System Levels I and II), 10 males and six females, between 10 and 16 years of age) undertook two trial of assessment of skeletal muscle function with one week inter-test interval. 14 ablebodies aged-and sex-matched (10 boys and four girls) served as controls, undertaking only one test at the first trial. Quadriceps maximal voluntary isometric force (MVIF) and isometric endurance time (IET; contraction time to exhaustion at 50% of MVIF) were measured twice one week follow another week. Muscle strength (test1: 115±18.5 vs. Test2: 115±20.9 Nm-1, p=0.458), (and control: 171.1±23.8m-1, p<0.01, respectively) endurance (test1: 94.80±20.48 vs. Test2: 94.80±20.47 sec., p=0.479), (and control: 106±35.63, p=0.85 and p=0.81 respectively), were reproducible during isometric contraction in children with hemiplegic CP. In conclusion, quadriceps maximal voluntary isometric force (MVIF) and isometric endurance time can help physician to measure strength in rehability service in children with hemiplegic CP.