[en] Stress relaxation measurements have been carried out on high density polyethylene (HDPE) and polycrystalline cadmium (Cd) after constant strain-rate loading at strain rates varying from 10^-6 to 10^-2 s^-1. When testing the applicability of a spectrum of relaxation times, increasing the straining time during the initial loading was found to cut off the initial part of the spectrum for HDPE; for Cd the spectrum remained largely unchanged, shifting its position towards longer times. The relaxation process was also analyzed using the exponential law of flow [rate approximately exp(sigma-sigmasub(i))] for the initial-, and the power law [rate approximately (sigma-sigmasub(i))sup(n)] for the final part of the curves. For Cd, the exponential region comprised the main part of the process, while it was less well developed for HDPE. In agreement with earlier results, the maximum slope, F, of the stress vs. ln time curves, was found to be related to the initial stress, sigma₀ as F approximatley 0.1 (sigma₀-sigmasub(i)), where sigmasub(i) is the initial stress. At the longest straining times used, a slight increase of this value was found. The value of sigmasub(i) was independent of strain rate; it increased with the strain. (Auth.)