  It is shown that the mixing of lepton doublets of the Standard Model can
yield sizeable contributions to the lepton asymmetry, that is generated through
the decays of right-handed neutrinos at finite temperature in the early
Universe. When calculating the flavour-mixing correlations, we account for the
effects of Yukawa as well as of gauge interactions. We compare the freeze-out
asymmetry from lepton-doublet mixing to the standard contributions from the
mixing and direct decays of right-handed neutrinos. The asymmetry from lepton
mixing is considerably large when the mass ratio between the right-handed
neutrinos is of order of a few, while it becomes Maxwell-suppressed for larger
hierarchies. For an intermediate range between the case of degenerate
right-handed neutrinos (resonant Leptogenesis) and the hierarchical case,
lepton mixing can yield the main contribution to the lepton asymmetry.
