Superplastic behaviors of an Al-Li-Cu-Mg-Zr alloy for aerospace application have been investigated over the temperature range 600-800K and the initial strain rate range 1×10^-4-1×10^-2s^-1. In cold-rolled and annealed sheet specimens having fine and equiaxed grains of about 5μm diameter, superplasticity was observed above 725K, wherein the maximum elongation of 480% appeared and the strain rate sensitivity was determined to be 0.45 at 800K. As-rolled sheet specimens became much more superplastic than annealed ones, when holding time prior to the tensile test was chosen appropriately. No improvement in ductility was found in the temperature increasing tensile tests. Extruded specimens having fine but elongated grain structure did hot show superplasticity at all, probably because grain boundary sliding was suppressed due to a geometrical reason.