Testing creation of matter with neutrinoless double beta decay

In this brief review, the importance of the so called {\em neutrinoless double beta decay} transition in the search for physics beyond the Standard Model is emphasized. The expectations for the transition rate are examined in the assumption that ordinary neutrinos have Majorana masses. We stress the relevance of cosmological measurements and discuss the uncertainties implied by nuclear physics. This work is based on the review paper of Ref.~\cite{rev}.