The relationships between seasonal changes in nutrients (N, P, K, Ca and Mg), binary nutrient ratios and production per tree has been studied in a late-harvest cultivar of peach (Prunus persica, Batsch cv. Calanda). The study has been carried out on 180 individual trees growing in the area of study (Bajo Aragon). The mineral analysis was repeated monthly during the growing season (May to October). Fruits from each tree were harvested and weighed separately. Trees were separated in two groups, productivity being higher or lower than 30.000 Kg ha-1. Seasonal changes in elements were similar for high and low production trees, excepting for K contents. Higher initial (60 days after flowering) K, Ca and Mg and lower Na and P contents appear to be statistically assocciated to higher production levels. Among the binary nutrient ratios used N/Mg, N/K, P/Mg, K/Mg, P/K appear to be useful for differentiating between high and low production trees. Mineral contents and binary nutrient ratios after 120 days of flowering, appear to be useful for diagnosis. However, data obtained in this work indicate that mineral contents and binary ratios only 60 days after flowering are best for diagnosis.Trabajo realizado al amparo del Proyecto CA-11/86 subvencionado por el CONAI (Diputación General de Aragón)Peer reviewed