The effectiveness of repeated applications of GA3 and streptomycin (SM) to stimulate seedless fruit development or reducing seed number per fruit of mandarin (Citrus recticulata Blanco cv Balady) were evaluated under field conditions at Motobus district, Kafr El-Sheikh governorate during 2014 and 2015 seasons. Trees were sprayed with GA3 at 25 ppm, SM at 250 ppm, SM at 500 ppm, SM at 250 ppm + GA3 at 25 ppm and SM at 500 ppm + GA3 at 25 ppm, while the control trees were sprayed with tap water. Results indicated that GA3 at 25 ppm recorded the highest fruit weight and acidity in both seasons. SM 500 + GA3 reduced seed number per fruit with about 76.66 and 77.46 % reduction in both seasons, respectively compared to the control. Meanwhile, high yield and fruit characteristics; firmness, vitamin C, brix and SSC/Acid ratio, were maintained under this treatment. The addition of GA3 to SM increased its efficacy in this respect.