We examine the importance of JP=1/2+,1/2- resonances for weak nonleptonic Ω- decays within the framework of chiral perturbation theory. The spin-1/2 resonances are included into an effective theory and the tree contributions to the Ω- decays are calculated. We find significant contributions to the decay amplitudes and satisfactory agreement with experiment. This confirms and extends previous results wherein such spin-1/2 resonances were included in nonleptonic and radiative-nonleptonic hyperon decays.