Fifteen patients with radiation-induced brachial plexus paralysis were studied. Thirteen women had been treated for breast cancer. Two men developed symptoms and signs following radiation therapy for lung cancer. The brachial plexus paralysis initially was not static and progressed, but spontaneous arrest with permanent residual paralysis was seen in three patients. Three were noted to have intractable pain, but the major complaint of the remaining 12 was the inability to use their hand. The ten patients on whom an earlier operation directed at the brachial plexus had been performed were not relieved. Two of these were later considered excellent candidates for a tendon transfer in the hand. One did not desire surgery. The other underwent operation and showed marked improvement of her grasp and general hand function.