An important rotor fault, which can lead to catastrophic failure if undetected, is fatigue crack in the shaft. Cracked rotating shafts have been the subject of studies and investigations for more than four decades, with some review papers published over this period. The aim of this paper is to discuss very recent developments of the research on cracked rotors, including the inverse problem of the identification of cracks in rotating machinery. © Springer Science+Business Media B.V. 2011.