This research aimed to study the wear amount and mechanism of a hydrodynamic journal bearing lubricated with magnetorheological (MR) fluid. The effects of bearing load, hard particle content in the MR fluid, magnetic field activation, and bearing sleeve material were experimentally investigated. Results revealed that the standard bronze sleeve experienced extreme wear with MR lubrication, two orders of magnitude higher than for oil lubrication, while the friction coefficient was almost 6 times higher, probably due to severe third-body abrasion. The least amount of wear among all tested materials was observed with a more flexible polymer sleeve, which showed ∼3.5 times more wear than the oil-lubricated bearing and a smaller increase in friction coefficient, around 2.6 times, as well as the formation of a possibly protective layer of crushed particles in the converging region of the film. The results suggest that polymers, and possibly also softer materials such as rubber, are a promising alternative for bearings lubricated with MR fluids under low-speed and high-load conditions.