A commercial CFD code is used to compute the flow field within the first stage impeller of a two stage axial flow pump. The code solves the 3‐D Reynolds Averaged Navier Stokes equations in a rotating cylindrical coordinate system using a standard k − ε turbulence model. Stage design parameters are, rotational speed 870 rpm, flow coefficient φ = 0.12, head coefficient ψ = 0.06, and specific speed 2.86 (8070 US). Results from the study include relative and absolute velocities, flow angles, and static and total pressures. Comparison is made to measured data available for the same impeller at two planes, one upstream of the impeller and the other downstream. The comparisons are for circumferentially averaged results and include axial and tangential velocities, impeller exit flow angle, static pressure, and total pressure. Results of this study show that the computational results closely match the shapes and magnitudes of the measured profiles, indicating that CFD can be used to accurately predict performance.