Two Higgs doublet extensions of the Standard Model predict the existence of charged Higgs bosons ( H^{+/-}). In such models  the branching  fraction for top quarks B(t->H^{+}b) can be large  thus  compiting with the SM decay t->W^{+}b.

This study presents the results of a search of charged Higgs in the decay products of the pair-produced top quarks. This search is based on the cross section measurements of ttbar production in three exclusive decay channels; the "dilepton" , "lepton + jets" and "lepton + hadronic tau" channel.

Assuming the charged Higgs decays to csbar, taunu and Wbbbar,  limits in the  t->Hb branching ratio are obtained. The interpretation of these results in the framework of SUSY theory and in a general Type II Two Doublet Higgs model are also presented.