Among the construction materials, wood reveals an orthotropic pattern, because of unique characteristics in its internal structure with three axes of wood biological directions (longitudinal, tangential and radial). elastic symmetry: longitudinal, tangential and radial, reveals an orthotropic pattern. The effect of grain angle orientation onin the elastic modulus constitutes the fundamental cause forof wood anisotropy. It is responsible for the greatest changes in the values of the constitutive tensor components, and, thus in the elastic constant values of wood. The goal of this article is to verify the adequacy of the orthotropic model for wood, basically expressed by the modulus of elasticity Ei related to a determined direction. It was considered a cCoordinate transformation between the materials axes (L, R and T) and Euler′s angles is considered to use a constitutive equation for orthotropic materials. The main purpose of this analysis is to theoretically explore the coordinate transformation in the three - dimensional point of view and also to statistically compare the results of modulus of elasticity from compression test in a Brazilian wood species, Guapuruvú (Schizolobium parahyba), with values obtained from a theoretical expression. The results from the analysis, in which the coefficient of determination (R-sq) was equal to 0.965 for a linear least squares analysis, showed that the orthotropic model is adequate to be applied