Abstract: A system for arm therapy comprises a first drive (M2) that can be fixedly connected to an element (10) determining the position of a user (19) and rotationally driving, about a first axis (A2), a part (21, 22, 23, 24, 25, M1, 26) of the arm therapy system which can be connected to an upper arm module (26, M3, M4). The driven part of the arm therapy system comprises a second drive (M1) adapted to rotationally drive said upper arm module (26, M3, M4) about a second axis (A1), wherein said second axis (A1) is oriented orthogonal to the first axis (A2). The system can provide a statically determined exoskeleton with correct anatomical axes and misaligned technical axes.