  We have investigated the role of localized {\it d} bands in the dynamical
response of Au, on the basis of {\it ab initio} pseudopotential calculations.
The density-response function has been evaluated in the random-phase
approximation. For small momenta, we have found a double peak structure in the
energy-loss function, which results from the presence of {\it d} electrons.
These results are in good agreement with the experimentally determined optical
response of gold. We also analyze the dependence of the dynamical structure
factor on the wave vector {\bf q}.
