  A system of two heavy fermions, leptons or quarks of the fourth generation,
which are bound together via the Higgs boson exchange is studied. The
conventional Yukawa-type interaction produced by this exchange is accompanied
by several important corrections. We derived the Hamiltonian, which describes
the correction arising from the retardation (compare the Breit correction in
QED); we also calculated the relativistic and radiative corrections. The
Higgs-induced bound state appears for the fermion mass m>m_{cr} \approx 500
GeV. When the long-range Coulomb interaction or the gluon exchange are
included, the bound states exist for any mass, but the Higgs exchange
drastically increases the binding energy of these states when m is approaching
m_{cr}. In the region m>m_{cr} the gluon exchange gives a sizable correction to
the Higgs induced binding energy. This correction greatly exceeds typical
binding energies in the states produced via the gluon exchange only. The
possibility of detection of the considered bound states at LHC is discussed.
