Gas dispersion impellers, such as the Rushton turbine and the more. recent concave blade turbines, all feature blades that are symmetric with respect to the plane of the disc. This despite the fact that the gas usually enters from the bottom, and thus causes a flow pattern that is distinctly asymmetric. This article discusses the performance of a gas dispersion impeller with blades that are vertically asymmetric, i.e. the blade: shape above the disk is different from the shape below the disk. It is shown that this impeller has a gassed power curve that is flatter than that of other impellers. Furthermore, it can disperse more gas before flooding than the impellers with symmetric blades.