The problem of cancellation of a nonstationary sinusoidal interference, acting at the output of a linear stable plant, is
considered. It is assumed that disturbance is a multifrequency narrowband signal, and that system output is contaminated with wideband noise.
 It is not assumed that the reference signal is available. Two disturbance canceling schemes are proposed, one for disturbances with unrelated frequency components, and the other one - for disturbances with interrelated components.  Simulation experiments confirm good tracking properties of the proposed control algorithms and their robustness to modeling errors.