In 2007 an experimental test program was initiated in order to evaluate the bond behaviour between concrete and ribbed steel bars under repeated load and transverse tension. Pull-out specimens with a longitudinal crack located along reinforcing bars were exposed to repeated pull-out loads. High cyclic tests, of up to one million load cycles, were performed for two different load levels and three different crack widths. The increase in slip (i.e., slip between steel rebar and concrete) relative to the number of load cycles was taken into account to compare various load conditions. The influence of transverse tension on bond resistance under repeated loading became evident. The wider the longitudinal crack widths resulting from transverse tension were, the greater the increase in slip and the sooner bond failure occurred. S-N curves for bond fatigue were derived for fatigue design based on slip development predictions.