Inhomogeneous corrosion in reinforced concrete is investigated using a beam with a flexural crack intersecting the reinforcement. An Evans diagram representation of the macrocell corrosion system is developed. The relationship between the current density and the potentials relative to the crack obtained from the Tafel polarization responses of active and passive steel in concrete compares favorably with the experimental values. When both microcell and macrocell mechanisms contribute to metal loss at the crack, the Evans diagram representation indicates that an increase in the macrocell current density results in a decreasing contribution from the local microcell at the macrocell anode. © 2010 Elsevier Ltd.