In the present paper, the possibilities of evaluating the deformation behaviour of powder mixtures during compression are investigated and interpreted. On the basis of deformation profiles relating pressure and deformation, the following parameters are discussed: maximum deformation (epsilon 0) at a compression stress equal to zero; relative maximum deformation (epsilon 0 divided by epsilon m) at a compresion stress equal to zero; elasto-plastic work of deformation (A epsilon); slope of the compression curve (tan alpha). When representing the change in pressure as a function of time, it becomes possible to determine the stress relaxation at constant deformation and to establish the socalled relaxation spectrum. The relaxation time (tau) is the time after which the stress is reduced to the e-th part of its original value. The aforementioned parameters for the evaluation of the behaviour of powder mixtures during compression yield, under laboratory conditions, valuable informations on the relaxation and the deformation of the substances under study which may be extrapolated to the deformation behaviour of tablets under the conditions of commercial production.