In general damping is estimated from impulse response obtained by giving small impact when the system is stationary (like a civil structure or a beam), this approach is well documented in many research works. In case of rotor-bearing systems such as a steam turbine, the damping estimated by impact is not identical to the damping observed during operation because of the angular acceleration effects. Since, it is not possible to obtain impact responses from a rotor bearing system operating at high speeds, one has to relay on signals obtained during operation which contain damping information. The present study compares conventional and time-frequency methods for estimating damping in rotor bearing systems from transient characteristics. Advantages of using time-frequency techniques over conventional techniques are focused.