  MACRO can detect three topologies of neutrino induced events, corresponding
to different parent neutrino energies. The most numerous sample is made of
upward throughgoing muons induced by atmospheric neutrinos of average energy
100 GeV. We have observed less events than expected events and the observed
zenith distribution does not fit the expected one in the no-oscillation
hypothesis, giving a maximum probability of 0.1 percent. Considering the
neutrino (numu-nutau) oscillation hypothesis the best probability (17 percent)
is obtained for maximum mixing and difference of square masses of a few times
10-3 eV2. The other detected samples are due to internally produced events and
upward-going stopping muons, corresponding to an average neutrino energy of
around 4 GeV. The results concerning these lower energy sample show a deficit
and a shape of the angular distributions in agreement with that predicted by
the oscillation model suggested by the higher energy sample. No evidence of a
neutrino signal due to dark matter particles in the direction of the core of
the Earth and of the Sun has been found among the background due to atmospheric
neutrinos and limits have been set. The neutralino hypothesis is investigated
and limits on its mass are given.
