A method of adaptively removing mainlobe clutter from range-Doppler data includes estimating the peak of the mainlobe clutter, and determining clutter regionboundaries adaptively and robustly. The mainlobe clutter peak may be estimated from the range-Doppler data, for example using both nonlinear and linear filters. Alternatively the mainlobe clutter peak may be estimated from knowledge of the position and speed of the vehicle, such as a missile, upon which the radar system moves. The clutter boundaries may be determined at each of the range bins by stepping along Doppler bins from the mainlobe clutter peak estimate in opposite directions, locating the boundary at locations off of the mainlobe clutter peak estimate that meet a given criterion. The method produces a finer determination of the mainlobe clutter region, resulting in less of the range-Doppler data being excluded as part of the mainlobe clutter region.