The high temperature creep behavior of mechanically alloyed Al-4Mg alloys dispersed with either Al₂O₃ or MgAl₂O₄ oxide particles were investigated. Because MgAl₂O₄ with spinel structure is thermally stable up to 2000℃, the material dispersed with MgAl₂O₄ could minimize the diffusional deformation and chemical reaction with the matrix at high temperatures. During mechanical alloying, the spinel was dispersed finer and more homogeneous than alumina in the matrix. In creep deformation, the spinel was found to be very effective to restrain the movement of dislocations and prevent the intergranular fracture due to grainboundary strengthening. Therefore, Al-4Mg alloy dispersed with spinel showed better creep resistance than that with alumina.