Ecophysiological, biochemical, anatomical and productional characteristics of sunlit and shady beech (Fagus sylvatica L.) leaves growing under different degree of immission impact were studied. Above mentioned characteristics were investigated in both undergrown individuals and adult trees. Significant differences were found for the net photosynthetic rate, transpiration rate, water loss rate, stomata density and chlorophyll content in relation to the degree of immission impact. Differences were observed also at some morphological and productional parameters of leaves (leaf area, specific leaf area and specific leaf mass) not only in a relationship to the different degree of immission impact but between the sunlit and the shady leaves, too.