This research was carried out in natural stands of sessile oak (Quercus petraea agg. Ehrendorfer 1967) on Miroc mountain. Three comunities were investigated: Pure sessile oak forest (Quercetum montanum Cer. et Jov. 1953. s.l.), sessile oak-common hornbeam forest (Querco-Carpinetum moesiacum Rud. 1949. s.l.) and sessile oak-balkan beech forest (Querco-Fagetum Glis. 1971). Pure sessile oak forests are found on the following soils: dystric ranker and acid cambic soil on sandstone, dystric ranker and acid cambisols on phyllite, and acid cambic soil on schists. Sessile oak-hornbeam forests grow on sandstone, granite and schists. Sessile oak-beech forests are found on acid cambisol on phyllite and sandstone conglomerate. Various ecological conditions (exposition, slope, altitude, soil types and bedrock) on Mt Miroc caused the occurence of diverse sessile oak forest communities, while different states of these forest stands resulted from the implementation of management measures.