The scope of this work is comparison of heights, gathered from lidar data and GNSS-levelling in the particluar area Prevalje under Krim. Three working places were chosen, that were assumed to be less favorable for laser scaning: a river's edge, a slope and a field with vegetation. The fourth was a level meadow, where the results should be equivalent on both modes of height determination: lidar and GNSS levelling. In the context of GNSS levelling we have performed measurements with the real time kinematic method. From those points (also for all four worksites) four surfaces were interpolated using natural neighbor method. The heights of the interpolated planes were then compared with digital terrain model, which is made on the ground of lidar's data. We found out that heights of above mentioned questionable areas are quite variable. Therefore, we believe that the quality of heights from lidar data at this particular area as well as in similar areas should be treated with special attention.