A new approach explaining the microhardness dependence on indentation load is pro- posed. It is assumed that the scale effect of microhardness is due to stage pattern of plastic strain and to gradual transition from the dislocation strain to the rotation one according to increasing force of indentor penetration. It is established that lubrication influence on the microhardness value is determined by stages of the microindentation process: at the loading stage, by modification in the structural condition of the surface metal layer in the indentor- metal contact region; at the unloading stage, by value of elastic recovery of stresses formed under loading. The joint action of both factors determines variations in the microhardness with the use of lubricant media. The same factors determine the microhardness dependence on indentation load value in lubricant media.