  Using data collected with the OPAL detector at LEP, we have searched for the
processes e+e- -> Z0 -> p e-, p mu- and the charge conjugate final-states.
These would violate the conservation of the baryon-number B, lepton-number L
and the fermion-number n = (B+L). No evidence for such decays has been found,
and the 95% confidence level upper limits on the partial widths Z0 -> p e and
Z0 -> p mu are found to be 4.6 and 4.4 keV respectively.
