  We review the status of the solutions to neutrino anomalies by
flavor-changing as well as flavor-diagonal neutrino interactions. While it is
difficult to explain the atmospheric neutrino data the solar neutrino data can
be well accounted for by the massless neutrino oscillation induced by such
non-standard neutrino interactions. We also discuss the possibility to test
such kind of interactions by the future neutrino oscillation experiments at
neutrino factories.
