Cu-Ni alloys form an isomorphous series of solid solution which find many applications in engineering industries specially under corrosive environments. Although, in many respects these alloys show close similarity to the pure metals, their mechanical behavior and corrosion properties differ considerably. The corrosion behavior of Cu-Ni alloys is critically reviewed, and the effect of structural heterogeneities, like lattice contraction, vacancies, coring and twinning on the corrosion behavior is examined.