An experimental study has been conducted to assess the effect of imposed small torsional oscillations on the creep behavior of Al-5 wt% Mg alloy during phase transformation. A series of tensile tests were conducted on the material with different levels of torsional oscillations and with different aging and matrix temperatures. The carefully designed experiments prove that increasing the shear strain amplitude of torsional oscillations and/or testing temperatures resulted in an increase of both transient and steady state creep parameters. The changes in work-hardening behavior of the samples with aging temperatures were rationalized in view of type, size, and distributions of phases existing in the original matrix. The results clearly show that the mechanism operating in the creep process was the precipitate-dislocation intersection. The microstructure of the samples studied was investigated by transmission electron microscopy.