The normal vascularization of peripheral nervesand the vascular factor in peripheral nerve les ons have regained increasing interest among surgeons. So, several attempts have been made to assess the relative importance of the vasa nervorum and intrinsic longitudinal vascular plexuses of nerve in maintaining the blood supply.of a segment of nerve trunk. The purpose of our experiment was to determine in laboratory animals the maximum extent to which a nerve can be mobilized without impairing its vascular supply so much that nerve function is jeopardized. All our studies were carried out on both sides of the sciatic-tibial nerve of thirty-two rabbit which were anesthetized intraperitoneally with urethane. The experimental procedure differed in three groups, Group I in which the sciatic nerve was mobilized 3 cm in length, Group II was mob lized 7 cm length and Group III was mobilized 10cm long. The tibialis post. muscles of each group were analyzed at intervals ot 1,2,4,6 and 8 weeks after neurolysis. Each muscles were examined grossly and histologically after hematoxylin and eosin staining. Experimental studies showed that a peripheral nerve is a well vascularized structure with a considerable reserve capacity in its microirculation. The intrinsic collateral system is well developeed and experimental deta supported the view that peripheral nerves may be mobilized over a cons derable length with or the only minium interference with their microvascular flow. The results were as follows: 1. The first evidence of histologic change in the muscle fibers was in the sarcolemmal neclei. 2. Localized atrophy of muscle fibers were observed at the six weeks after neurolysis. 3. With increasing length of neurolysis, abnormal finding were developed in early stage. 4. Massive atrophy of muscle fibers were noted in the muscle fibers which neurolysed more 7cm.