  A new ansatz of democratic lepton mixing is proposed at the GUT scale and the
radiative corrections to its phenomenological consequences are calculated at
the electroweak scale. We demonstrate that it is possible to obtain the
experimentally favored results for both neutrino masses and lepton flavor
mixing angles from this ansatz, provided the neutrino Yukawa coupling matrix
takes a specific nontrivial pattern. The seesaw threshold effects play a
significant role in the running of relevant physical quantities.
