It is natural to ask why the market for interns in the United States of America has to be cleared with a centralized matching procedure (the NRMP) and how this rationing procedure affects equilibrium wages. This paper presents a model in which a market failure is caused by insufficiently differentiated wages. The NRMP solves the problem but it enables the hospitals to extract more surplus from their interns than they could in an ideal competitive equilibrium. It is demonstrated that this distortion causes welfare losses if the hospitals can substitute between physicians and interns. Copyright 1998 by Economics Department of the University of Pennsylvania and the Osaka University Institute of Social and Economic Research Association.