The invention relates to an upper limb rehabilitation system for rehabilitating an upper limb of a subject and comprising a mobile platform coupled to a fixed platform. The mobile platform comprises an articulate handle assembly movable, during a rehabilitation session, within a plane which is substantially coplanar or parallel to the transverse plane of the subject, wherein the handle assembly (10) is provided with a gripping device (11) comprising a shaft (18) The articulate handle assembly (10) according to the invention comprises: a supporting structure having a first and a second holding elements (14, 15) pivotally connected together to rotate about a first axis of rotation (θ1) perpendicular to said transverse plane; a third holding element (16) connected to said supporting structure; and a fourth holding element (17) supporting the shaft (18) of the gripping device (11) and pivotally connected to said third holding element (16) to rotate about a second axis of rotation (θ2) which is perpendicular to the first axis of rotation (θ1). Said first and second axis of rotation (θ1, θ2) as well as the central axis (θ3) of the shaft (18) of the gripping device (11) always intersect each other at one point independently from the orientation of each of the first, second, third and fourth holding elements (14, 15, 16, 17).