  The selfcoupling of the Higgs field grows with the mass of the Higgs particle
and induces potentially large radiative corrections in the electroweak model.
The technical aspects of performing multiloop calculations in the massive case
are discussed briefly. I review the status of two-loop calculations of
radiative corrections of enhanced electroweak strength which are relevant for
the Higgs physics. I discuss the relevance of the existing results with respect
to heavy Higgs searches at future colliders and their implications regarding
the validity range of perturbation theory.
