The influence of previous corrosion on fatigue crack initiation has been determined. Cylindrical specimens and flat specimens with a central hole of the aluminium alloy T075-T6 were corroded in a 3.5 % NaC1 solution. The cylindrical specimens were tested under constant amplitude loading while for the specimens with a central hole a block programme loading was used. It appeared that the reduction in fatigue life was caused by fatigue crack initiation in an early stage, from corrosion pits.