Hardness together with abrasivity is quite often used in the field of wear resistance as the criteria for judging surfaces of the alloys, castings, hardfacings and overlays. This research is devoted to the investigation of microhardness phenomena of poly (ethylene terephatalate) (PET) blends with polyolefins and thermoplastic elastomers. The effect of radiation modification and chemical compatibilization (polypropylene grafted maleic anhydride) on the microdeformative and structural properties of the investigated compositions was determined. It was concluded that micromechanical properties of the investigated compositions – especially those with higher PET content – were strongly dependent from the crystallinity of polyester. By increasing PET content in the investigated multiphase systems universal microhardness and microhardness modulus increased, but microcreep decreased, that allowed assume that wear resistance of the compositions also increased. Besides it was found out that as a result of radiation modification microhardness of the investigated compositions increase.