  In the standard model, CP asymmetries in the $B^\pm \to \pi^\pm K$ channels
are about 2% based on perturbative calculation. Rescattering effects might
enhance it to at most (20-25)%. We show that lepton-number-violating $\lambda'$
couplings in supersymmetric models are capable of enhancing it to as large as
100%. Upcoming B factories will test this scenario.
