We compute a unitarity bound for higgs mass using one--loop corrected s--wave
partial amplitude for ZLβZLββZLβZLβ scattering. We use the
equivalence theorem and show that the higgs mass has to be less than β600 GeV in order to save the (perturbative) unitarity in the higgs' resonance
region. We also discuss about the validity of perturbation expansion in the
symmetry breaking sector.Comment: 6 pages, LaTeX, figures available upon request, TURKU-FL-P