Given the increased use of accelerometers in movement analysis, validation of such inertial sensors against conventional 3D camera systems and performance comparisons of different sensors have become important topics in biomechanics. This paper evaluates and compares linear acceleration trajectories obtained from two different 3D accelerometers and derived from Vicon position data for an upper limb "reach & grasp" task. Overall, good correspondence between the three measurement systems was obtained. Sources of error are discussed.