Introduction: Pistachio is one of the most important horticultural crops in Iran, USA, Turkey and some Mediterranean countries. Some physiological problems such as abscission of inflorescence buds, blankness, nonsplitting, early splitting, cracking and nut deformation reduce the pistachio yield and quality. A proper nutrition management of pistachio orchard might decrease the physiological problems and increasing the yield. Calcium is an essential plant macro-nutrient that has several distinct functions within plants. These functions can be divided into main areas including effects on membranes, enzymes, cell walls, and interactions of calcium with phytohormones. Free polyamines (putrescine, spermine, spermidine), are the widely distributed of N containing organic molecules binding to the intracellular anions (DNA, RNA, chromatin and proteins). They are also known to possess several regulatory functions. In plants, they have been associated with regulating many physiological processes, such as organogenesis, embryogenesis, floral initiation and development, leaf senescence, fruit development and ripening, and abiotic and biotic plant stress responses. Although the spray application of calcium compound and free polyamine has been investigated separately, application of calcium compounds combined with free polyamines has not been investigated yet. Therefore, the aim of this study was to evaluate the effect of combined treatments of calcium and free polyamines on decreasing the physiological problems and improving the yield of ‘Ahmad-Aghaii’ pistachio trees…