Abstract
We investigate the longitudinal lepton polarization asymmetry in the exclusive processes B-Kl + l - and B-K*l + l - . We include both short- and long-distance contributions to the asymmetry in our discussions. We find that average values of the polarization asymmetries of the muon and τ for B→K ( * ) μ + μ - and B→K ( * ) τ + τ - are -0.8 (-0.7) and -0.2 (-0.5), respectively.