In the Mediterranean regions, oak forests are commonly used for livestock grazing. However, it is well documented that livestock grazing is an essential factor that can affect the success of natural regeneration of oak and other woody species of the understorey. Consequently, it influences the composition and structure of oak woodlands. The main objective of the present study was to examine the effects of grazing intensity on characteristics of oak seedlings establishment (density, height, number of leaves) and on the diversity of the woody species seedlings. The research was conducted in open canopy Quercus frainetto woodland, grazed by a herd of 500 goats for eight months per year, located in Evros region, north-eastern Greece. The distance from a goat corral was used to represent relative grazing intensity. In May 2016, vegetation measurements were made along transects placed at 50, 150, 300, 600 and 1200 m from the goat corral, running perpendicular to four replicates. According to the results, increased grazing intensity significantly reduced the density, the plant height and the number of leaves of Quercus frainetto seedlings. Grazing intensity did not affect significantly diversity, evenness and dominance indices for the woody species seedlings. However, heavy grazing reduced species richness and the Chao1 index.