Since the recent convincing evidence for massive neutrinos in oscillation experiments, the next task is to determine the absolute masses of neutrinos. A unique pattern of neutrino masses will be hopefully fixed in the
future superbeam experiments and neutrino factories. However, the determination of the exact scale is more complicated and depends on the mass of the lightest neutrino (m„)min. If (rnv)min > 0.35 eV, the future tritium
/3 decay experiments (e.g. KATRIN) will have a chance to establish absolute neutrino masses. For smaller masses, 0.004 eV< (m„)min < 0.35 eV, if neutrinos are Majorana particles, an additional information can be derived from the neutrinoless double /3 decay (/3/3)0i/ of nuclei and again the absolute neutrino masses can be fixed. If, however, (m„)min < 0.004 eV, none of the present and foreseeable future experiments is known to be able to fix the mass scale.