Compressive properties of the open cell 6063 aluminum alloy foams made by the plaster molding process were investigated before and after heat treatment. Loading process was controlled at a displacement rate of 2 mm/min. Compressive strength of 10 PPI foam was the largest of the same density foams. Increase in strength after heat treatment for the bulk material was remark able, however was not for the 6063 aluminum foam. C values were in the range of $0.39{sim}0.53$ for as cast foams and $0.13{sim}0.16$ for T6 heat treated foams in the equation of ${sigma}^*_{pl}/{sigma}_{ys}=C({ ho}/{ ho}_{s})^{1.5}$ and increased with cell size.