Two field experiments on wheat ( Triticum aestivum L.) c.v. Gemmiza-9 were conducted to study the effect of different concentrations of sitosterol (100, 150 and 200 mg/i ) , ethrel ( 0, 100 and 150 mg/I ) and their interaction on growth, photosynthetic pigments, yield and its components as well as some blo-chemical constituents of wheat plant. The data indicated that spraying sitosterol especially with concentrations (150 and 200 mg/i ) at all stages resulted in significant increases in plant height, number of tillers, number of spikes, blades area/plant, flag leaf area, dry weight of plant, photosynthetic pigment contents spike length, grain index, grain and straw yield per plant & per fed, crop index and harvest index. On the other side, spraying ethrel at the moderate and higher concentrations (100 & 150 mg/I ) led to significant decreases in plant height, both number of tillers and spikes/plant, flag leaf area, blades area/plant . Whereas dry weight / plant was significantly increased. The higher concentration of sitosterol (200 mg/i ) and the lower concentration of ethrel (50 mg/i) produced the highest values in most of growth characters at the different stages, while spraying plant with 200 mg/i sitosterol and 150 mg/i ethrel recorded the highest values ¡n ecoiomic yield and its components as compared with other treatments. Application of sitosterol or ethrel treatments ¡n general had a positive effect ¡n most cases on protein and total carbohydrate contents. The highest protein content recorded by the higher concentration of both sitosterol200 mg/i or ethrel 150 mg/i while the lower ones (100 mg/i sitosterol & 50 mg/ ethrel ) resulted ¡n the highest values of total carbohydrate content. The interaction between sitosterol at the moderate & higher concentrations and all ethrel concentrations caused significant increases in plant height, dry weight/plant, blades area/plant, flag leaf area, photosynthetic pigments ( at the different stages of growth ) spike length and crude protein in most cases, while total carbohydrate was significantly increased under the lower & moderate concentrations of sitosterol and ethrel treatments. The results has been interpreted by the correlation coefficient between wheat plant characters under sitosterol or ethrel treatments which indicated that grain yield was positively and significantly correlated with plant height, number of tiller/plant, spike length, flag leaf area, 100 — grain weight, grain & straw yield per plant, harvest index arid chemical content of grains.