Neutrino masses are so small that it has been not possible to observe them directly. However recent experiments have shown that both the electron neutrinos produced in the solar energy cycle, as well as the muon neutrinos produced in the interactions of cosmic rays in the earth’s atmosphere can “oscillate” to other neutrino flavours before their detection a long distance away. The wavelengths of the oscillations are related to the neutrino masses, and their amplitudes to the “mixing angles” which relate the neutrino states with the well defined flavour to the states of well defined mass. The masses and mixing angels may give clues to the symmetry relationships between the three particle families, at present not understood at all. I will try to give a brief account of the experimental results.