The anisotropic properties of Zr-2.5 wt % Nb pressure tube material, used in pressurized heavy water reactors (PHWR) depend primarily on the texture associated with the material. Particularly properties such as coefficient of thermal expansion, mechanical anisotropy, irradiation growth, stress corrosion cracking, and delayed hydrogen cracking, are directly correlated. Thus, the knowledge of preferred orientation becomes an essential prerequisite for property evaluation. In the present paper the correlation between the preferred orientation factor, namely Kearn's f parameter, and some of the important properties of the material is summarized. The f parameters were deduced from the X-ray diffraction data, using the inverse pole figure method, and then subsequently the values were verified experimentally using the direct pole figure method. Copyright © 2007 by ASTM International.