The GaAs (113)A and ( 1 ̄ 1 ̄ 3 ̄)B surfaces were prepared by molecular beam epitaxy (MBE) and ion bombardment and annealing (IBA). The surfaces were investigated in situ by means of low-energy electron diffraction and surface core-level (SCL) spectroscopy. Both orientations show 1×1 reconstructions after preparation with IBA. For the (113)A face a stable, 8×1 reconstructed surface was prepared by MBE. SCL shifts (SCLSs) are observed for As3d (+0.53eV) and Ga3d (−0.46, +0.36eV) which support a recently proposed model by Wassermeier et al. [Phys. Rev. B 51 (1995) 14721]. The (113)A(8×1) surface exhibits surface resonances at −1.0 and −3.8eV below the valence band maximum. The dispersion of these resonances is only weak and does not follow the symmetry of the reconstructed surface. The ( 1 ̄ 1 ̄ 3 ̄)B surface shows { 1 ̄ 1 ̄ 1 ̄}B and {110} facets after preparation with MBE. This is confirmed by SCLSs for As3d (−0.63, +0.57eV).