Aging characteristics of the alloy Al-1.0 wt.% Mn-0.28 wt.% Fe have been investigated in the temperature range 400-550 degrees C by resistivity measurements. Pre-cold working was found to have considerable effects on the isothermal characteristics of the alloy. The activation energy of vacancy migration in the first stage of aging was found to decrease on cold-working, its value ranging between 0.35 and 0.50 eV depending on the thermal and mechanical history of the alloy. A resistivity peak has been observed in the second range of aging and this has been ascribed to a clustering process. The precipitation process in the third stage of aging was found to be enhanced by cold-working, the energy activating this process being reduced by cold-working and ranging between 0.28 and 0.50 eV. Flat needle-like precipitates of Al₆Mn were observed by TEM examination after prolonged aging.