There has been an urgent need for an effective and efficient upper limb rehabilitation method for poststroke patients. We present a Micro-Sensor-based Upper Limb rehabilitation System for poststroke patients. The wearable motion capture units are attached to upper limb segments embedded in the fabric of garments. The body segment orientation relative to the reference frame is computed by fusion of the sensory data, and the upper limb trajectory and movement parameters are obtained. Using the micro-Sensor-based Upper Limb rehabilitation System, the clinical Active Range of Motion scale can be measured automatically; a set of novel quantitative measures, referred to as motor feature indices, are obtained to evaluate the quality of the movement. Experimental results show that the proposed motor feature indices reflect the real motor impairment status very well, providing objective measurements of a patient's functional recovery status in the rehabilitation process.