The influence of steel–concrete interface defects on reinforcing steel corrosion is discussed. The defects that are analysed relate to the gaps caused by bleeding, settlement and segregation of fresh concrete under horizontal reinforcing bars. These defects increase 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 characterised by the ultimate bond strength recorded in a pullout test and by the defect length under the reinforcement measured with a videomicroscope. There was good correlation between these two methods. The corrosion was measured by the resistance of polarisation and corroded surface area. It is concluded that the quality of concrete and steel–concrete interface, decreasing with height of concrete section, directly affects the corrosion rate. 29 refs.