Are neutrinos Dirac or Majorana particles?

In spite of the general belief that neutrinos are Majorana particles, their character should be revealed experimentally. We begin by discussing why it is so difficult in terrestrial experiments. If neutrinos are Majorana part icles, the first signal should come from neutrinoless double beta decay. St ill the search for such a decay of various nuclei is negative. We outline h ow the present knowledge of neutrino masses and mixing matrix elements comb ined with the bound from (beta beta)(0v) decay could help to determine thei r nature.