The present study examines the microstructure and formability of homogenized and unhomogenized AA8011 aluminum alloy sheets under uniaxial and biaxial deformation modes. The stretch formability of sheets has been characterized in terms of limit strains in forming limit diagrams (FLDs). The formability of the material is associated with combinations of strain hardening, strain-rate hardening and surface roughening which is developed during the plastic deformation of the material. The phenomenon of recrystallization and the effect of second phase particles has been investigated in cold rolled sheets. It appears that surface roughening which is in turn a result of the grain coarsening is more important in the homogenized materials annealed at high temperatures. (C) 2004 Kluwer Academic Publishers.