Down syndrome (DS) is the most common chromosomal disorder which is characterized by decreased muscle tone or hypotonia. The purpose of this study was to identify the effect of a nursing intervention on muscle tone of children with Down syndrome. The Design of this study was quasi-experimental research design. A purposive sample of 60 children diagnosed with Down syndrome was selected to carry out this study. This study was conducted at three centers for children with special needs in Shebin El-Kom and Tala city. In Shebin El-Kom, it conducted at El Basma and Wogod centers for children with special needs. In Tala city, it was conducted at El Basma center.Two instruments were used for data gathering .A structured interview questionnaire involved children`s characteristic such as age , sex ,associated problems with DS. The second tool was Arm, Leg, and Trunk muscle tone scale . The results of this study indicated that, nursing intervention in the form of therapeutic massage improved muscle tone of children with Down syndrome on posttest. Conclusion, this study concluded that children who received , nursing intervention in the form of therapeutic massage had better muscle tone than children who didn't receive therapeutic massage. Therefore, it is recommended that, nursing intervention in the form of therapeutic massage should be applied to improve muscle tone of children with Down syndrome.