This paper tries to assess the ability of UAVs equipped with RGB cameras to monitor the stability of the specific slopes in the surface lignite mines of Ptolemaida basin. For this purpose, the results of high measurement accuracy surveying, which was applied based on a series of target prisms placed on the crests of mine benches, are compared with the displacements detected by subtracting successive digital terrain models produced using UAVs equipped with RGB cameras in combination with RTK processing.