We derive the one-loop effective action induced by a heavy top in models with
an extended Higgs sector. We use the effective action to analyze the top
corrections to the ρ parameter and to the Higgs-gauge boson couplings. We
show that in models with ρ=1 at tree-level, one does not lose
generally the bound on mt from the ρ parameter.Comment: 9 pages, phyzzx file, UPR-0603T. (a new reference has been added