The study aimed to show if the permanent forests are different from the forests that growed on former agricultural land in the Bieszczady Mountains, southeastern Poland. It is important to investigate how different tree species react in former agriculture land and which are more adaptable to the given environmental conditions, in order to choose the most appropriate tree species and to develop strategies for optimal restoration of forest ecosystems. The results show differences in forest structure and parameters between the two categories. The post-agricultural forest had a much wide variety of tree species and a higher Shannon-Weaver diversity index value (3.06 vs. 2.53). The density of live stems were insignificant higher in the postagricultural forest, but the total live volume per hectare was higher in the permanent forest, with a difference between hardwood species, which had higher values in the post-agricultural forest, and softwood species which had a higher live volume in the permanent forest. However, the density and volume of snags were found to be much higher in the post-agricultural forest