Some results of the development of a technique for determining the undergrowth height from the values range of interferometric phase based on the TerraSAR-TanDEM-X single-pass survey data are presented. The test site is a clearing in the middle of a pine forest along a power line in a mountainous area. Comparison of satellite and subsatellite measurements of the height of young growth at the test site showed the need to take into account the density and breed composition of vegetation.