  We investigate the importance of final state interactions in weak nonleptonic
hyperon decays within a relativistic chiral unitary approach based on coupled
channels. The effective potentials for meson-baryon scattering are derived from
a chiral effective Lagrangian and iterated in a Bethe-Salpeter equation, which
generates the low lying baryon resonances dynamically. The inclusion of final
state interactions decreases the discrepancy between theory and experiment for
both s and p waves. Our study indicates that contributions from higher order
terms of the weak effective Lagrangian may play an important role in these
decays.
