  The supersymmetric QCD corrections to the hadronic width of a heavy charged
Higgs boson, basically dominated by the top-quark decay mode $H^{+}\rightarrow
t \bar{b}$, are evaluated at ${\cal O}(\alpha_s)$ within the MSSM and compared
with the standard QCD corrections. The study of such quantum effects, which
turn out to be rather large, is essential to understand the hypothetical
supersymmetric nature of a heavy charged Higgs boson potentially produced in
the near future at the Tevatron and/or at the LHC.
