Neutrino Mass Spectra, CP-Violation and Neutrinoless Double Beta-Decay

Assuming 3-neutrino mixing and massive Majorana neutrinos, we present some implications of the neutrino oscillation solutions of the solar and atmospheric neutrino problems and the results of the CHOOZ experiment for the predictions of the neutrinoless double-beta decay rate. If the present or upcoming searches of neutrinoless double-beta decay give a positive result, the Majorana nature of massive neutrinos will be established. From the determination of the value of the effective Majorana mass, it would be possible to obtain information on the neutrino mass spectrum. With additional information on the absolute value of neutrino masses, it might be possible to infer if CP-parity is violated in the lepton sector.