  We consider the two Higgs doublet model extension of the Standard Model in
the limit where all physical scalar particles are very heavy; too heavy, in
fact, to be experimentally produced in forthcoming experiments. The symmetry
breaking sector can thus be described by an effective chiral Lagrangian. We
obtain the values of the coefficients of the O(p^4) operators relevant to the
oblique corrections and investigate to what extent some non-decoupling effects
may remain at low energies.
