Interferometric TanDEM-X data are used together with high-resolution, airborne lidar-derived digital elevation models (DEMs) to produce digital canopy models (DCMs) for the boreal forests of Remningstorp and Krycklan, situated in southern and northern Sweden, respectively. An overview of interferometric data processing is given. First results showing the potential of TanDEM-X-based forest canopy mapping are presented. It is concluded that baselines giving height-of-ambiguity values in the order of 50-80 meters are preferable, although factors such as angle of incidence and along-track baseline are also of importance. Clear-cuts can easily be detected thanks to the high resolution of TanDEM-X imagery. Seasonal variations of scattering height are most visible for deciduous trees, where the scattering height is significantly lower in the winter, probably due to the lack of leaves.