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Exoskeletons with active joints arouse great interest for human power augmentation and assistive applications. In this article we present an innovative prototype of a portable shoulder and elbow exoskeleton, for assistance in agricultural tasks and heavy lifting in general. This exoskeleton provides controlled torque for the flexion/extension movements of shoulders and elbows and passive actuation of the movement of abduction and adduction of the shoulder. The remaining degrees of freedom of the shoulder system have been left unrestricted for comfort and little discrepancy with arm and shoulder movement. For this purpose, a serial mechanism has also been incorporated to facilitate scapular movement. On the other hand, the design incorporates a parallelogram beam mechanism to reduce the actuation torques and improve the controllability of the device. Moreover, the mechanical design of this mechanism was improved to ensure alignment between user elbow average flexion/extension rotation axis and that of the mechanism during the complete range of motion.