  Neutrinoless double beta decay, lepton number violating collider processes
and the Baryon Asymmetry of the Universe (BAU) are intimately related. In
particular lepton number violating processes at low energies in combination
with sphaleron transitions will typically erase any pre-existing baryon
asymmetry of the Universe. In this contribution we briefly review the tight
connection between neutrinoless double beta decay, lepton number violating
processes at the LHC and constraints from successful baryogenesis. We argue
that far-reaching conclusions can be drawn unless the baryon asymmetry is
stabilized via some newly introduced mechanism.
