The rat brachial plexus was studied morphologically and the average numbers of the fascicles were studied by light microscope. For this purpose, we used 30 Wistar albino adult rats (16 males, 14 females; 180-250 g). The rats were anaesthetized by urethane (0.6 ml/100 g body weight injected i.p.). The brachial plexus was prepared for the microdissection technique and was evaluated in terms of its formation. Sections of the origin level of roots (C-5, C-6, C-7, C-8 and Th-1) and the terminal branches (ulnar, median, radial (musculospiral), axillary (circumflex), and musculocutaneous nerves) were taken and the average numbers of fascicles were calculated.