Background. There is evidence for violation or a complete change in the arm swing cycle during walking in a number of pathologic conditions. Aim. We assess the functional state of the shoulder and elbow joints in normal conditions and with joint hypermobility syndrome (JHS) using the kinematic instrumental method of analyzing gait. Material and methods. We studied 27 adolescent girls 1215 years old with JHS and healthy subjects. A Vicon motion capture analysis system (Vicon, Oxford, Great Britain) was used to record biomechanical parameters. Results. A decrease in limb movement amplitudes was noted in the shoulder joint around the frontal and sagittal axes in patients with JHS compared to the norm. During the arm swing cycle in the normal state, the shoulder is in a state of internal rotation, whereas in the girls with JHS, the shoulder is in a state of external rotation for most of the arm swing cycle. The elbow joint in the JHS subjects showed a significant increase in flexion angle of the forearm in the swing phase of 41.5 0.90 and a decrease in this angle in the stance phase. The JHS group also showed a decrease in power of the muscles acting on the shoulder joint. Conclusions. A common sign of changes in the range of motion of the links of the upper limb in the shoulder and elbow joints in subjects with JHS was decreased amplitude of their flexion and decreased power of the joints. In the adolescents with JHS in the shoulder joint, a significant decrease in the internal rotation angles and reduction of the limb was found.