The norm of elastic constant tensor and the norms of the irreducible parts of the elastic constants of Zn structure semiconductors are calculated. The relation of the scalar parts norm and the other parts norms and the anisotropy of the material are presented. The norm ratios are used as a criterion to present the anisotropy degree of the properties of the material. The ratio (N / C°) is calculated, where N is the norm of elastic constant tensor of the material and C° is the elastic constant of the crystal in the order of magnitude e2 / r4, where e is the charge of the electron, and r is the distance between the nearest neighbor atom. Also the comparison of (N / C°
) with Zinc Blender lattice parameter, Zinc Blende density and Energy Gap at 300 K are given in (Radwan, 2001).