  We discuss quantum corrections of new physics to the triple coupling of the
lightest CP-even Higgs boson in the Two Higgs Doublet Model (THDM) and also in
the Minimal Supersymmetric Standard Model (MSSM). In the THDM, quartic
contributions of the mass of heavy particles in the loop can appear, which are
not absorbed by renormalization of the Higgs boson mass. Such non-decoupling
effects on the self-coupling can give corrections of ${\cal O}(100%)$, even
when all measured Higgs couplings with gauge bosons and fermions are consistent
with the Standard Model prediction. In the MSSM, the loop-corrections decouple
in such a scenario.
