Indentation is a relatively simple and virtually nondestructive technique of assessing mechanical properties of materials by an indenter inducing localized deformation into a solid surface. The load-displacement curves, the hardness, and the elastic modulus data together with associated analysis for poly(ether ether ketone) (PEEK) surfaces are presented as a function of contact displacement. The major conclusions are that nanoindentation into the polymer show a surface hardening response that is dependent upon the contact conditions. PEEK, a semicrystalline polymer, has bimodal nanoindentation characteristics because of the presence of hard crystalline lamella within a softer amorphous phase. The bimodal character is confirmed by the load-displacement, the hardness, and the elastic modulus data. The semicrystalline polymer exhibits periodic fluctuations in mechanical properties with the increasing penetration depth. Finally, the nanoindentation is found to be a convenient method to estimate the degree of crystallinity of semicrystalline polymers. The technique may provide a convenient means to understand morphological description of the polymeric surfaces. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4401-4409, 2013