The redundant kinematic structure of upper extremity (UE) provides it with increased dexterity in activities of daily living (ADL) Most functional tasks during ADL can be implemented in various positions however only some routine trajectories are employed in healthy humans Exploring motion ability and analyzing dexterity are clinically helpful in understanding the motion principles of the UE during ADL The aim of this work was to develop a qualitative and quantitative evaluation method for unconstrained movement analysis of the UE Ten healthy male volunteers with no UE pathology were tested based on a kinematic model proposed in this paper which follows the ISB recommendations The dexterity measure (DM) and manipulability ellipsoid (ME) were used to evaluate the dexterity distribution and motion ability in space Representative dexterity trajectories and corresponding ellipsoids were determined for the ADL tasks The results of the study showed that there was a most dexterous posture for each functional task The UE movement followed an approximately optimal kinematic performance trajectory when the hand moved in front of the thorax during ADL Crown Copyright (C) 2010 Published by Elsevier B V All rights reserved