  This study examines the influence of the fourth generation quarks on the
double lepton polarizations forward--backward asymmetries in B \rar K^\ast
\ell^+ \ell^- decay. We obtain that for both (muon, tau) channels the magnitude
and the sign of the differential forward--backward asymmetries and the
magnitude of the average forward--backward asymmetries are quite sensitive to
the 4th generation quarks mass and mixing parameters. It can serve as a good
tool to search for new physics effects, precisely, to search for the fourth
generation quarks(t', b') via its indirect manifestations in the loop diagrams.
