Aerated mixing of shear thinning and elastic fluids with helical ribbon impellers in the laminar and transition flow regimes has been investigated. Various Newtonian, shear-thinning inelastic, viscoelastic and non-shear-thinning elastic fluids have been chosen to assess the influence of complex rheological properties on the power requirement. For the first time, the power requirement in non-shear-thinning elastic fluids is shown to be larger in gassed systems than in ungassed fluids, while a decrease of power is observed for the shear-thinning inelastic fluids. The gassed power is also dependent on the gas flow rate and Reynolds number. Two correlations are proposed in the laminar and transition flow regimes, respectively, to predict the power consumption as functions of the Reynolds number defined for aerated non-Newtonian fluids, the aeration and Weissenberg numbers. Gas hold-up, bubble size and bubble behaviour have also been studied.