An efficient polynomial interpolation method is proposed to reduce the computational burden of the coregistration of synthetic aperture radar images in interferometric processing. The method can be viewed as an application of the Farrow interpolator technique and requires a series of 2-D fast Fourier transforms (FFTs). Mainly, it has two advantages relative to the usual coregistration procedure. First, it does not require to compute or store in memory any kernel sample. Second, it involves less floating-point operations than the conventional coregistration, with a clear advantage if the image needs to be oversampled. The efficiency of the method is based on the fact that the complexity of one 2-D FFT is much smaller than the complexity of one spatial convolution. These advantages are demonstrated by both analyzing the interpolation procedure itself and by defining an efficient code implementation.