Experimental and theoretical studies of lifetimes and transition probabilities for Au and relativistic multiconfiguration Dirac-Fock (MCDF) calculations of lifetimes and transitions probabilities in this ion. The work was motivated by significant disagreements between previous experimental 5d<SUP>9</SUP>6p lifetimes, obtained by means of the beam-foil (BF) method and theoretical data based on Hartree-Fock calculations in which relativistic effects were included as perturbations. The new measurements, based on laser-induced fluorescence, support the BF data and are also in excellent agreement with the MCDF results. We confirm that, while computational methods which include perturbative relativistic corrections appear to be adequate for moderately heavy elements such as Ag, fully relativistic calculations are essential for describing systems as heavy as Au.