The presence of small amounts of apparently physiologically significant nitrate‐N in citrus leaves was demonstrated. Nitrate‐N and total N were determined and compared in citrus tree leaves receiving different rates of N and, in one case, additional P and K fertilizers. The nitrate‐N in the leaves showed a close relationship with the N fertilizer rate. In P and K fertilized trees, nitrate‐N content was also affected by these two elements.