A diffuser with an “exit length” is one with a channel of uniform cross section following the diffuser. Tests were made of different diffusers with and without exit lengths. The data were for steady, incompressible, two-dimensional flow. The performance of each diffuser was improved by the presence of an exit length. As compared to flow without an exit length, flow with an exit length is characterized by a reduced boundary-layer growth, by a small decrease in the pressure rise across the diverging section, and by a decrease in the static-pressure gradient at the diffuser inlet.