Leaf nutrient concentration is a factor that influence the irregular production or alternate bearing in pecan trees. The purpose of this study was to evaluate the leaf nutrient concentration and its relationship with the nut production in pecan trees during three years. The results indicated that pecan tree plantations showed deficiencies in the following nutrients: zinc, phosphorus, potassium and iron. The lowest nut production (1047 kg/ha) coincided with the highest nutritional imbalance (161), factor wich probably influenced the nut production. As the nut production per hectare increased, nitrogen, phosphorus, potassium and iron leaf concentrations and the kernel percentage (edible parte) were reduced in each year of the study. This response suggest that in the highest nut production years, there is a higher demand of nutrients, and at the same time, the quality (kernel percentage) is reduced.