LDA measurements and CFD predictions of the flow in a vessel stirred by a Rushton impeller are reported. The predictions employed a rotating mesh around the impeller and a stationary mesh in the remainder of the vessel. The experimental and numerical results are compared and discussed. It is shown that the mean velocity field is well reproduced quantitatively by the CFD model; the turbulence field is well predicted qualitatively across the whole vessel and quantitatively in the bulk flow region but differences between experiment and calculation are found near the impeller blades. Both the measurement and prediction methods are assessed.