  We discuss applications of the dispersion quark model to exclusive
semileptonic decays of heavy mesons. The transition form factors in this
relativistic formulation of the quark model are given by double spectral
representations through the wave functions of the initial and final mesons both
in the scattering and the decay regions. An important feature of the model is
that the form factors have the correct behavior in accordance with QCD in the
case of meson decays induced by heavy parent quark transition both to heavy and
light daughter quarks. We demonstrate that the dispersion quark model gives
results compatible with the lattice calculations at large $q^2$ and thus
provides reliable form factors in the whole decay region.
