Some main national varieties or endangered old cultivars from six countries (13 from France, 12 from Greece, 10 from Italy, 6 from Portugal, 8 from Spain and 8 from Slovenia) were analysed for phenolic composition within the framework of the SAFENUT (Safeguard of hazelnut and almond genetic resources: from traditional uses to novel agroindustry opportunities) European project. Using a high-performance liquid chromatograph (HPLC) with a diode array (PDA) detector, the content of the phenolics was analyzed in extracts from the kernels. Gallic, chlorogenic, sinapic, p-coumaric, ferulic and ellagic acid, as well as epicatechin and rutin, were individually identified in all tested cultivars. Large variations of phenolic contents were noted between cultivars. Intercultivar variability was the most evident in sinapic, ellagic and p-coumaric acid, as well as in rutin. ’Casina’ from France had the highest sum (251.01 mg/kg) of all the identified phenolics. In contrast, ’Polycarpos’ from Greece, was the poorest with phenolics et al. (49,16 mg/kg). Ellagic acid, one of the most important polyphenolic antioxidants, appeared in concentrations between 0.56 mg/kg (’Polycarpos’, Greece) and 18.55 mg/kg (’Purpurea’, Portugal). On the chromatograms, two additional compounds were found, expressed as the equivalent of chlorogenic acid. They were the most abundant phenolics in all the studied cultivars. An improved method, MS-HPLC will be used next year with the aim of identifying them individually.