Large amplitude neutrino oscillations with Majorana mass eigenstates

The problem of nonvanishing neutrino mass and its origin is discussed. The possible Majorana mass of neutrinos might be indicated by detection of large amplitude and probably large oscillation length neutrino oscillations which might be expected naturally in theoretical schemes using Majorana mass terms. The recent and near future neutrino oscillation experiments are analysed concerning the detectable Majorana masses assuming different theoretical schemes, e.g. coexistence of Majorana and Dirac mass terms. (D.Gy.)