  We consider the decay modes of the heavy $q^\prime\bar{q^\prime}$ bound
states originating from Higgs boson exchange between quark -- anti-quark pair.
In case of a small coupling between the fourth and lower generation the main
decay mode is $q^\prime\bar{q^\prime}$ annihilation. We show that for a vector
state the dominant decay modes are Higgs-gamma and Higgs-Z decays, while for a
pseudoscalar state the strong two-gluon decay mode dominates. The bound states
are very narrow. The ratio of the total width to the binding energy is less
than 1% if we are not extremely close to the critical quark mass where the
binding energy is very small. The discussed decay modes exist for any
fermion-antifermion bound states including heavy leptons and heavy neutrinos if
their masses are high enough to form a bound state due to attractive Higgs
boson exchange potential.
