Objectives: Our aim was to investigate the morphologic and morphometric features of brachial plexus in rat and to evaluate the findings with that of the human in classical textbooks comparatively.Methods: This study was carried out on 100 brachial plexuses of 50 adult wistar albino rats (240-280 gr) (25 males and 25 females). The overlying tissues were incised for the evaluation of brachial plexus in the axillary region. After then brachial plexus was prepared with the microdissection technique and evaluated in terms of its formation. We made the measurements related to the brachial plexus and extremities; length of upper (anterior) extremities, length and width of axillary region, brachial plexus, and roots of spinal nerves. We also noted the formation shape of brachial plexus.Results: We found that the brachial plexus of rat was formed by C5, C6, C7, C8 and Th1 spinal nerves. Sometimes, fibers from C4 might connect with C5. The formation of brachial plexus at root level varied from each other in rats. On the other hand, some roots were thick while some of them were thin in shape. Of the contributing spinal nerves to the brachial plexus (C5-8, Th1), mean width was between 0.7-1.1 mm, mean length of merging to the trunk was 2.2-4.06 mm, while mean width of brachial plexus was 7.8 mm, mean length was detected as 9.5 mm. There was significant correlation with respect to p<0.05 and p<0.01 between the length and width values of the upper extremity and the values of the brachial plexus itself as well as the spinal nerves forming the plexus. In the histologic examination, mean axonal count was between 4000- 4500 in each mm2 at the level of spinal nerve roots. The diameter and the number of axons were inversely proportional to each other.Conclusion: Comparative knowledge on the morphometric and morphologic features of brachial plexus in rat and human can help the investigators to achieve successful results in experimental surgery.