Two techniques for the adaptive cancellation of clutter in pulse radars are considered. The first, based on the maximisation of the signal/interference improvement, leads to an eigenvector problem; simpler suboptimal structures according to a straightforward model with a minimum number of parameters are considered. The second, based on the linear prediction of the interference, leads to a whitening (or prediction error) filter. The basic performance of both techniques is evaluated in a typical radar environment of two clutter sources.