During hydraulic devices operation, centrifugal and magnetic forces often affect local density changes in magnetorheological fluid, depending on operating conditions and the composition of the fluid. The density distribution of the magnetorheological fluid in the vessel is measured in order to assess the density changes induced by centrifugal and magnetic forces. Two magnetorheological fluids selected for the tests differ in composition and iron particle size. The density of the magnetorheological fluid is measured in a rotating vessel, and after applying a magnet to a wall of a stationary vessel. During rotation, the magnetorheological fluid is denser near the vessel walls, where the radius of the rotating fluid is the largest. Moreover, it is noted that (both during spinning and after applying the magnet) the density changes of the magnetorheological fluid are not instantaneous, but occurs over time.