An adaptive notch filter design that considers the body-bending vibration associated with the attitude control of a two-stage sounding rocket is discussed in this paper. The algorithm adapts the parameters while keeping the poles of the notch filter inside the unit circle on the z-plane, and it satisfies the stability conditions of the filter at all times. Only a single parameter of the filter is adapted to simplify the algorithm to speed up the convergence rate. Applying this adaptive notch filter to the two-stage sounding rocket results in stable response characteristics of the attitude control system, which is unstable without adaptation. (C) 2000 Published by Elsevier Science Ltd.