  We report on a precise computation of the topological charge distribution in
the SU(3) Yang--Mills theory. It is carried out on the lattice with high
statistics Monte Carlo simulations by employing the definition of the
topological charge suggested by Neuberger's fermions. We observe significant
deviations from a Gaussian distribution. Our results disfavour the theta
behaviour of the vacuum energy predicted by instanton models, while they are
compatible with the expectation from the large Nc expansion.
