Characterizing the differences between the mechanical properties of brain tissue gray and white matters is of importance in biomechanics of brain tissue and may find a variety of different applications in medicine. In this study, a comparison has been made between mechanical behavior of bovine brain tissue white and gray matters. Through a linear elastic theory and using Bridgman method, necking phenomenon is considered for brain tissue in tension test. Results show that gray and white matters have different mechanical properties and differences between true and nominal values (the effect of cross section changes of the samples during the test) are not negligible. Besides, it is shown that for certain strains, linear elastic theory is acceptable for brain tissue modeling. These results are in agreement with the literature. © 2008 Science Publications.