GaSb(001) surface reconstructions with the experimentally observed (2×10) and c(2×10) symmetry are investigated employing density functional theory. Total energy calculations are carried out for a significant number of reconstructions, including the previously suggested metallic structures and new models which fulfill the electron counting rule. Special attention is given to the incorporation of Ga atoms during the initial steps of growth. It is shown, that none of these reconstructions is thermodynamically stable. This suggests that (2×10) and c(2×10) structures are kinetically stabilized under experimental conditions. [DOI: 10.1380/ejssnt.2009.429]