In order to determine the effects of non-uniformity of oxide dispersion on the mechanical properties of sintered aluminum powder alloys, two series of the alloys containing the same amounts of oxide, having different uniformity of dispersion, were prepared by powder metallurgy process. The experiments were conducted mainly for the comparison of their ductilities.Reduction of the uniformity resulted in the decrease of yield strength at room temperature, but in the marked increase of ductility for the alloys containing less than 7% (vol.) of oxide. The results of tensile tests were compared for the two series of the alloys up to 500°C. It was shown that the alloys of nonuniform dispersion had little dependency of ductility on temperature, but exhibited a large amount of work by tensile deformation in plastic region. Hardness of non-uniform dispersion alloys revealed higher thermal stability in the heat-treatment after cold rolling, as compared with that of uniform dispersion alloys having considerably high thermal stability as extruded material. The results of density measurement and fractographical observation of tensile fracture suggested that brittleness at high temperatures was closely related to the void formation due to gases released by the decomposition of hydrated aluminum oxide in the aluminum powder.It is concluded that appreciable improvements in mechanical properties of these alloys can be expected by proper control of uniformity of oxide dispersion and also by preliminary degassing treatments of powder before compacting process.