An aluminum-lithium alloy AA8090 was deformed under superplastic condition to investigate the effect of strain, strain rate and test temperature on deformation anisotropy and microstructural evolution. The plastic anisotropy ratio was found to increase towards 1 with the increase in strain and strain rate. The initially elongated microstructure with rolling texture underwent dynamic recrystallization and tended to become equiaxed with cubic or random texture during superplastic deformation. The grain size increased with increasing strain and test temperature but decreased with the increase in strain rate. Such microstructural changes and the mechanisms involved in superplastic deformation, including the dislocation-based accommodation process, are suggested to develop isotropy. © 2000 Elsevier Science S.A.