The abundance and diversity of forest understory vegetation can be significantly impacted by forest management. Besides having a wide geographical distribution in Turkey, the Oriental beech (Fagus orientalis Lipsky) is also one of the economically important timber species of the country. The aim of this study is to compare the understory herb layer communities of mature and young beech stands which regenerated as a result of the shelterwood method. We studied understory plant species diversity and composition in 16 plots in old and young beech stands in Belgrad Forest near Istanbul, Turkey. We found no significant differences between the two stand types in understory plant diversity but understory species compositions in two stand types were found to be different. Our finding can be useful for forest management planning; by focusing on stand scale to achieve forest management conserving understory plant diversity in a forest.