Orange yields and the size of the fruits harvested in the years 1961 to 1964 were related with the content of nitrogen, phosphorus, potassium, and calcium in six-month old leaves collected each year in a long-term experimental orchard with Baianinha orange trees (Citrus sinensis,Osbeck), at the Citrus Experiment Station of Limeira, State of São Paulo. The trees were budded on sweet orange rootstock (C. sinensis,Osb.) in a factorial experiment NPK 3X3X3 started in 1951. The average weight or size of the fruit was calculated from the weight record and the total number of fruits from each plot or treatment. The influence of applied fertilizers on foliage composition and tree response (production, fruit size) was also reported. Analysis of variance of the data obtained revealed several differences due to the fertilizer treatments to be significant, as can be seen in table 1. The following correlations were found to be significant: 1. Leaf nitrogen with yields (weights), r = 0.35**. 2. Leaf nitrogen with number of fruits, r = 0.40**. 3. Leaf nitrogen with fruit sizes (average weights), r = - 0.36**. 4. Leaf potassium with fruit sizes (average weights), r = 0.52**. 5. Leaf calcium with fruit yields (weights), r = 0.51**. Leaf phosphorus was not significantly correlated with yields (weights), number of fruits, or fruit sizes.