In order to experimentally analyze the influence of a small symmetry break on the degeneracy of discrete energy levels we have carried out STM/STS investigations on triphenylphosphine molecules (P(C6H5)3) adsorbed to Au(111) surfaces. The measurements were performed with a variable‐temperature UHV‐STM which was operated at 6.5 K. From the experimentally obtained I(V) data the energy‐level distribution is derived for individual molecules and a symmetry‐reduction‐induced decrease of the level degeneracy can be observed in detail and compared with former results. © 2003 American Institute of Physics