This paper deals with a solution to the problem of shaking force and shaking moment balancing of planar four-bar linkages. The conditions for balancing are formulated by the minimization of the root mean square (r.m.s.) value of the shaking moment. The method is based on displacements of the axes of rotation of the counterweights connected to the crank and rocker. The ef ciency of the suggested method is illustrated by a numerical example in which a reduction in the shaking moment of 76 per cent is achieved.