The purpose of this research was to study diversity of woody species in the Sweet chestnut (Castanea sativa L.) forests, Guilan, north of Iran. These forests are located in the Shafaroud and Emamzadeh Ebrahim regions. The Emamzadeh Ebrahim region is consisted of Visroud, Kishkhaleh, Askeh Koh, Male Lab, Doroudkhan, Galeroudkhan, Siahmazgy and Mali Anbar sites. Sampling was done in a selective ... [Show full abstract] manner in each site with a plot area of 50 m × 50 m for tree and shrub layers and a circle 1000 m2for tree saplings. In each plot, all trees ≈ 10 cm in diameter at breast height (DBH) were identified and the DBH was measured, and shrub and tree sapling species were identified and recorded. In total, 68 sampling plots were taken using GPS device in the two regions. The results revealed that the mean richness, Simpson's index, Hill's N2' Shannon Wierver's function and N1 were higher in the Shafaroud region than other sites in tree, shrub and tree sapling layers. The highest and lowest mean values of evenness were obtained in the Kishkhaleh and Askekoh sites, respectively in tree layer, and similarly were in the Askekoh and Visroud in the shrub layer. The highest and lowest mean values of evenness were obtained in the Male Lab and Askeh Koh, respectively in tree sapling layer.