This article deals with the influence of steel–concrete interface defects on reinforcing steel corrosion. The defects that are analyzed in this paper relate to the gaps caused by bleeding, settlement and segregation of fresh concrete under horizontal reinforcing bars. These defects are increasing with the concrete depth below the horizontal reinforcement and depend on the bleeding capacity of concrete mixture. Various concrete mixtures including self-compacting concrete (SCC) were tested. The defects at the interface were characterized by the ultimate bond strength recorded in a pullout test and by the defect length under the reinforcement measured with a videomicroscope. The results indicate a good correlation between these two characterization methods. The corrosion was measured by the resistance of polarization and corroded surface area. The results allow us to conclude that the quality of concrete and steel–concrete interface, decreasing with height of concrete section, affects directly the corrosion rate.