  We analyze the unconventional top quark decay mode t -> H^+ b at the quantum
level within the context of general Two-Higgs-Doublet models by including the
full electroweak effects from the Yukawa couplings. The results are presented
in the on-shell renormalization scheme with a physically well motivated
definition of tan(beta). While the QCD corrections have been taken into account
in the current experimental analyses of that decay, the electroweak effects
have always been neglected. However, we find that they can be rather large and
could dramatically alter the interpretation of the present data from the
Tevatron collider. For instance, in large portions of the parameter space the
electroweak effects prevent the Tevatron data from placing any bound at all to
the charged Higgs mass for essentially any value of tan(beta).
