This study was carried out to determine stomatal distribution and density in leaves of 18 Turkish hazelnut cultivars. Stomata were detected only on the lower leaf surface (hypostomatous). The number of stomata varied between 83.08 (Kalinkara) and 117.73 (Sivri) per mm(2). The length and the width of stoma in the cultivars were within the ranges of 22.00-27.45 mu m and 17.00-22.61 mu m, respectively. The longest and the widest stoma were measured in Yassi Badem. Among the cultivars, Sivri had the highest stoma index (17.15%) while Kalinkara had the lowest (10.55%). The number of epidermal cells varied between 567 and 681 per mm(2). There were negative correlations for number of stomata with the stoma length (-0.407) and with stoma width (-0.380). The results showed that hazelnut cultivars have a unique stoma features which might be important in varietal identification.