  We study the decay rate and the CP violating asymmetry of the exclusive B->
pi ell+ ell- and B-> rho ell+ ell- decays in the case where one of the final
leptons is polarized. We calculate the contributions coming from the individual
polarization states in order to identify a so-called wrong sign decay, which is
a decay with a given polarization, whose width and CP asymmetry are smaller as
compared to the unpolarized one. The results are presented for electron and tau
leptons. We observe that in particular decay channels, one can identify a wrong
sign decay which is more sensitive to new physics beyond the Standard Model.
