Vibration generated from rolling element bearings and gears can lead to complex signals which sometimes can be masked by several other machine components, processes or operating conditions in the machine. This can obscur their detection and diagnostic, hence the need sometimes for more advanced methods of analysis. In this paper, many such cases will be presented, taken mainly from rolling-mills in the steel industry and the mining and transportation industries. A comprehensive summary of bearing fault detection and diagnosis will be discussed in line with upcoming ISO standards on the diagnostic methods for rolling element bearings.