We present an analysis of spherical depth sensing indentation. In this paper, the Oliver and Pharr methodology is applied to the experimental load-displacement curves and those obtained numerically for determining hardness H and Young’s modulus E. The numerical results are obtained by BEM code. The observed variations with respect to load of the elastic modulus and the hardness as obtained by the Oliver and Pharr methodology are correlated with plastic zone shape. In the case of isotropic homogeneous material, numerical results show that almost constant elastic modulus is obtained when the plastic zone has developed up to the free surface. In the case of elastic (very hard) coating on an elastic perfectly plastic substrate, plastic deformation in the latter is followed by reverse plastic flow during unloading leading to a decrease in the calculated value of hardness