Getting Information on |U_(e3)|² from Neutrino-less Double Beta Decay

We consider the possibility to gain information on the lepton mixing matrix element |U_{e3}| from an improved experimental limit on the effective neutrino mass governing neutrino-less double beta decay. We show that typically a lower limit on |U_{e3}| can be set. Furthermore, we give the values of the sum of neutrino masses and |U_{e3}| which are allowed and forbidden by an experimental upper limit on the effective mass. Alternative explanations for neutrino-less double beta decay or Dirac neutrinos would be required if future measurements showed that the values lie in the respective regions. Moreover, we argue that a measurement of |U_{e3}| from neutrino-less double beta decay is very difficult due to the expected errors on the effective mass and the oscillation parameters.