The use of microsurgical techniques is essential in peripheral nerve surgery, in which dissection at the fascicular level is required. Magnification with an operating microscope allows for an accurate evaluation of the severity of the trauma to the nerve tissue and permits atraumatic interfascicular dissection. Fascicular or interfascicular dissection and repair with the use of nerve grafts was carried out in 220 peripheral nerve lesions of the upper extremity. Our results of nerve-grafting in the upper extremity (median, ulnar, and radial-nerves) indicate an inverse association between the age of the patient and the delay between injury and grafting. In addition, we found that nerve grafting without tension produces superior results over simple neurorrhaphy under tension and permits better axonal growth and nerve recovery.