Abstract: A system for arm therapy of a user comprises a device for determining the position of the user, a first drive, an upper arm rotation module, an upper arm cuff, at least one hinge movably connecting the upper arm cuff and the first drive, a second drive, and a rotation drive provided on the upper arm rotation module itself. The upper arm cuff is connected to the arm of the user and has a substantially hollow-cylindrical shape when it is closed. The first drive and the second drive are adapted to place the upper arm rotation module in a defined spatial position, and the rotation drive is adapted to turn the upper arm cuff about its main axis relative to the outer part of the upper arm rotation module.