This paper presents two methods for ground-penetrating radar (GPR) imaging of land mines: a two-dimensional (2-D) seismic migration method and a 3-D nonlinear inverse scattering method. The seismic migration technique has been successfully applied to processing field data sets collected at a test site. The results show that the seismic migration technique is a useful real-time imaging method. To image the 3-D structure of the land mine, we have developed a full 3-D nonlinear inverse scattering algorithm on the basis of the contrast source inversion method. To account for the ground surface and potentially other subsurface layers, the inverse scattering method uses a multilayered medium as a background. Preliminary results demonstrate that the 3-D inverse scattering method can successfully provide high-resolution reconstruction of high-contrast buried objects.