Given the nutritional and nutraceutical characteristics of hazelnuts fruits, its production has grown, as well as the profit obtained by the hazelnut growers worldwide. Nowadays, there are 1,078,192 hectares of hazelnut trees in the world, and it is also one of the most widespread fruit trees in Chile. To improve overall yield, various agronomic management techniques have been developed, such as fertilization management. To adjust nutrient application doses, tissue analysis must be done, but most of the reference standards have been developed in edaphoclimatic conditions that do not represent all the hazelnut growing areas worldwide. This study evaluated during three consecutive seasons the concentration of nutrients in hazelnut leaves of cv. 'Barcelona' in three high-yield orchards in productive conditions of southern Chile. The results indicated that the concentration of most of the nutrients evaluated had variations that were due to the month of sampling. N, P and K showed a decrease in their concentration from October to April, while Ca and Fe increased their concentration for the same period. Non clear trends or few concentration changes were recorded for the other nutrients. Most of the nutrients were within the 'normal' range compared to international standards, except fog Mg and Ca, which were found as 'deficient' and 'below normal,' respectively. Finally, the results of this research do not constitute a nutritional standard for hazelnut cv. 'Barcelona,' but contribute to have reference values to adjust fertilization management in the edaphoclimatic conditions of southern Chile.