  We perform a global three generation analysis of the current solar and
atmospheric evidence in favor of neutrino oscillations. We also include the
negative results coming from CHOOZ to constrain the nu_e mixing. We study the
zones of mass-mixing oscillations parameters compatible with all the data. It
is shown that almost pure nu_mu <--> nu_tau oscillations are required to
explain the atmospheric neutrino anomaly and almost pure nu_1 <--> nu_2
oscillations to account for the solar neutrino deficit.
