The permanent dipole moment of para-amino benzoic acid has been calculated at various theoretical levels, including Hartree-Fock, second-order Moller-Plesset perturbation (MP2), coupled cluster singles and doubles (CCSD), and triples corrections CCSD(T), and hybrid density functional theory at B3LYP level. It is found that the B3LYP method fails to provide correct results for the geometry and the permanent dipole moment. These results are significantly improved by MP2 calculations. Our best estimated dipole moments obtained at CCSD and CCSD(T) levels are in good agreement with experiment. (C) 2004 American Institute of Physics.