  We compute the low energy threshold corrections to neutrino masses and mixing
in the Standard Model (SM) and its minimal supersymmetric version, using the
effective theory technique. We demonstrate that they stabilize the
renormalization group (RG) running with respect to the choice of the scale to
which the RG equation is integrated. This confirms the correctness of the
recent re-derivation of the RGE for the SM in hep-ph/0108005. The explicit
formulae for the low energy threshold corrections corrections can be applied to
specific models of neutrino masses and mixing.
