This paper deals with the dietary behaviour and the tree species preference in the river bank stands in the diet of established population Eurasian Beaver (Castor fiber L., 1758) in the environment of Oderské vrchy; the objective is to assess the suitability of this environment for future development of the Eurasian Beaver and to asses the influence of the beaver’s dietary behaviour on the river bank stands. In the monitored area, the total of 5 tree species with the following preference were recorded: willow (Salix) 42.2%, aspen (Populus) 28%, dogwood (Comus) 15.5%, birch (Betula) 7.4% and alder (Alnus) 6.9%. The most damaged diameter interval recorded within the all damaged tree species ranges from 2.6 to 6 cm, followed by the interval 6.1–12 cm. Over 61% of the trees felled by the beaver had a bigger diameter. The most sensitive reaction to beaver’s dietary behaviour was shown by aspen (reduction of numbers by 27.6%) and by willow (reduction of numbers by 16.6%) on the monitored area.