Compressors, turbines and other rotating machines often have long thin shafts which may cause vibration problems. An electromagnetic damper placed on the rotor of a machine represents one method of controlling high levels of vibrations. This paper discusses experimental results of an electromagnetic damper placed on a small three mass test rotor. Experimental data was taken for cases with the damper at three different locations on the highly unbalanced rotor to study the effectiveness of the damper in controlling vibrations at the first and second rotor bending modes and at a pedestal response mode. Reductions of vibrations up to 88%, 40%, and 19% were achieved for the first critical speed, second critical speed, and pedestal response mode, respectively. Values of magnetic damper stiffness and damping used to obtain these reductions were only a small fraction of the fluid film bearing damping and stiffness properties.