This investigation was carried out during the two successive seasons of 2013 and 2014 in a private orchard located at "New Gamgarah, Benha" district, Qalyubeia Governerate to study the effect of some stimulating substances i.e., (GA₃, NAA, sea-weeds, yeast extract and proplis) at different concentrations on some fruiting parameters and fruit properties as well as leaf nutritional status of Washington navel orange trees budded on sour orange reatstock. Trees under study were 18-year-old, grown in a clay leamy soil and planted at 5 meters apart under flood irrigation system. Obtained results revealed that all investigated stimulating substances treatments under study as foliar spray at various concentrations resulted in a significant increase in fruit set percentage and yield either Kg/tree or ton/feddan as well as the yield increment % in relation to the control, however decreased the percentage of fruit drop in comparison with the control during both seasons of study. Moreover, both fruit physical characters such as (fruit weight, volume, height, diameter and fruit shap index) and fruit chemical properties (TSS %, total acidity and TSS %, /acid ratio)  were significantly improved as a result of sprayed trees with the above mentioned stimulating substances treatments. In addition to that, leaf nutrient contents were improved in all studied treatments from the standpoint of statistic as compared to the control during both the first and second seasons of study. Generally, it could be concluded that, most of investigated treatments resulted in a positive and significant effect on most studied properties, since both treatments of  active dry yeast at (150 and 100 ml³/L)were the most effective treatments for increasing both fruit set % and productivity while decreasing fruit drop % as well as improving both the most studied of fruit properties and leaf nutrient contents of Washington navel orange trees