  The difference between the timelike and spacelike meson form factors is
analysed in the framework of perturbative QCD with Sudakov effects included. It
is found that integrable singularities appear but that the asymptotic behavior
is the same in the timelike and spacelike regions. The approach to asymptotia
is quite slow and a rather constant enhancement of the timelike value is
expected at measurable large \(Q^{2}\). This is in agreement with the trend
shown by experimental data.
