The aim of this paper is to identify the location of fatigue extrusions and intrusions, the latter being the precursor of short microcracks in a fully pearlitic steel. The material contains a huge amount of interfaces, as it consists of α -ferrite bands separated by Fe3C cementite lamellae. Fe3C cementite remained inactive while cyclic plasticity occurred in α -ferrite bands. Both intrusions and extrusions formed in the interior of the α -ferrite bands. Unlike other materials, intrusion did not nucleate at the interface between α -ferrite and Fe3C cementite. The coherency of the interface is suspected to be responsible for this shift.