The effect of π-π interaction in isospin-zero states on the characteristics of the ω-->ππγ decay is investigated by means of partial-wave dispersion relations. With the ρ-exchange contribution as the driving term and elastic unitarity for π-π scattering on the right-hand cut, we arrive at integral equations whose solutions explicitly depend on the π-π phase shift. Various scattering-length and resonance models are used to represent the π-π phase shift. The high-energy contribution to the integral equation is treated in three ways: by subtraction, adding an effective pole on the left-hand cut, and normalizing the amplitude at the f0 resonance to a Veneziano model for ω-->ππγ. Numerical results for rate and spectrum are discussed in the light of the possibility of discriminating by experimental results among the various models for π-π interaction.