Enhancement of substitutional diffusion is observed in a brass (30 wt% Zn) by following the decrease in electrical resistivity with neutron irradiation of a thermally equilibrated alloy; the decrease arises from the increase in short- range order. It was determined by previous research that this diffusion enhancement is largely caused by the annealing of radiation-produced vacancies in excess of the thermal equilibrium concentration. Therefore, the results reported here are based upon a well-established technique.