The evolution of strength at the initial stages of sintering is considered both theoretically and experimentally. Theoretically, the strength properties are assessed accounting for hardening due to the growth of the interparticle necks during sintering and softening due to the increase of the temperature. Experimentally, the strength properties are determined for steel powder specimens using a three-point bending test simultaneous to sintering, The calculated and the experimental results are compared and possibilities of the elaboration of a criterion of the engineering strength under sintering are discussed. Both the model and the experiments for sintering under bending yield values for material strength that should be intermediate between the strength of a powder compact during free sintering and the strength of a finished sintered product.