Field experiments were performed at the Agricultural Experiments and Researches Station, Faculty of Agriculture, Cairo University, Giza, Egypt during the two growing seasons of 2005/2006 and 2006/2007 to study the effect of foliar application with stigmasterol at various concentrations of 0, 20, 40, 80 and 160 ppm on flowering onset as well as on morphological, anatomical and yield characters of Egyptian lupine cv. Giza 2. Results obtained could be summarized in the following: 1-  Stigmasterol at relatively low used concentration of 20 ppm showed no significant effect on flowering onset of Egyptian lupine cv. Giza 2. While, the other three assigned concentrations (40, 80 and 160 ppm) of stigmasterol shortened significantly the period to flowering in both studied seasons without significant differences among them. 2-  Stigmasterol at relatively low used concentration of 20 ppm or at relatively high used concentration of 160 ppm showed no significant effect on all studied morphological characters in the two investigated seasons. Whereas, foliar application with any of the two assigned median concentrations of 40 and 80 ppm stigmasterol induced significant promotive effects on plant height, main stem length and number of internodes of the main stem. While, number of branches was increased significantly when stigmasterol was sprayed only with 80 ppm in both studied seasons. 3-  Stigmasterol at any of the two adopted median concentrations of 40 and 80 ppm had a significant promotive effect on yield and most of yield components (number of pods and seeds per plant) of Egyptian lupine cv. Giza 2 in the two growing seasons of investigation. 4-  The highest percentage of crude protein (31.94%) was recorded in seeds of lupine plants sprayed with 80 ppm stigmasterol (the control recorded 26.47% crude protein in their seeds). By contrast, the lowest percentage of total alkaloids (3.68%) was recorded in seeds of lupine plants sprayed with 80 ppm stigmasterol (the control recorded 4.86% alkaloids in their seeds). 5- The increase in stem diameter of Egyptian lupine cv. Giza 2 due to foliar application with 80 ppm stigmasterol could be attributed to the prominent increase in stem wall thickness as well as in diameter of hollow pith. The increase in stem wall thickness could be attributed to the prominent increase in all included tissues (the thickness of epidermis, cortex, fiber strands, vascular tissue and parenchymatous area of the pith). Likewise, spraying stigmasterol at concentration of 80 ppm increased thickness of both midvein and lamina of leaflet blades of  Egyptian lupine cv. Giza 2. The increase in lamina thickness was accompanied with increments in thickness of palisade and spongy tissues. Also, the main vascular undle of the midvein was increased in size as a result of spraying stigmasterol.