Background: After a stroke, the patient may have abnormal muscle tone due to abnormal alignment. Physical therapists have used stretching, neural mobilization other methods to treat patients after stroke. In addition, joint mobilization is also used to stimulation in pathway of cervical segmental region and to normal cervical spine alignment. Objects: The purpose of this study was to determine whether Maitland cervical spine mobilization has an immediate effect on muscle tone and stiffness of upper extremity. Methods: Thirty subjects were divided into a experimental group (n1=10), a placebo group (n2=10), and a control group (n3=10). The Maitland cervical spine mobilization was applied in the supine position. Immediately after the intervention, muscle tone and stiffness of biceps brachii, brachioradialis, deltoid, and pectoralis major were measured using Myoton®PRO. In the placebo group, sham mobilization was applied to the fifth and sixth cervical vertebra, and the control group was instructed to control breathing. Results: In the experimental group, significant differences were found in muscle tone and stiffness of biceps brachii and brachioradialis in comparison with the affected side and the non-affected side before the intervention (p<.05), whereas there was no significant difference after the intervention (p>.05). Muscle tone of biceps brachii on the non-affected side and pectoralis major on the affected side was significantly decreased before and after the intervention (p<.05). The placebo and control group showed no changes on the non-affected and affected side, and no significant differences were detected before and after the intervention. All the groups revealed no significant differences in muscle tone and stiffness of upper extremity before and after the intervention. Conclusion: This study suggests that the application of Maitland cervical spine mobilization enhanced muscle tone of upper extremity on the involved side symmetrically, and influenced a decrease in muscle tone