Abstract: Ferrography is important for monitoring the condition of machinery by analyzing the ferromagnetic debris contained in lubricating oil. However, non ferromagnetic debris cannot be deposited effectively through the magnetic field of the ferrography. Thus the working conditions of the sliding bearings of a mining hoister were monitored, with an emphasis on the effect of magnetic fluid in ferrography on the deposition of non magnetic particles. It has been found that the non ferromagnetic wear debris was deposited effectively in the presence of the magnetic fluid. This makes it possible to obtain more and adequate information of the wear debris with the ferroghraphy. Moreover, the magnetic fluids showed selectivity in terms of their "magnetizing effect" on the non magnetic wear debris. To summarize, the magnetic fluids can be effectively used for the monitoring of the non magnetic particles in ferroghraphy.