Egyptian puberal buffalo bulls (n=9); aged 15-18 months; allocated into three groups (n= 3/group) to verify the effect of different doses (8 μg, 12 μg or 16 μg) of GnRH analogue (Buserelin acetate) on the sexual desire and semen characteristics. Bulls treated with 12 μg of Buserelin were superior to those injected with 8 µg or 16 µg where it shortened the reaction time (6.51±0.38min. vs. 7.48±0.41min. and 7.46±0.40min., respectively) and improved the semen quantity: increased the ejaculate volume (2.22± 0.13ml vs. 1.89± 0.13 ml and 1.54±0.11ml, respectively) and sperm cell concentration (957±86.60×106 sperm/ml vs. 928±86.76×106 sperm/ml and 779±53.62×106 sperm/ml, respectively), improved the sperm motility (57.13±1.36% vs. 63.29±1.55% and 56.11±1.51%, respectively) and sperm livability (66.80± 1.23% vs. 69.12± 1.45% and 67.85± 1.87%, respectively), and lower sperm abnormalities (5.08±0.33% vs. 11.30± 0.95% and 9.16±0.49%, respectively). Instead, Buserelin injection increased testosterone levels in a dose-dependent-manner (1.73±0.57ng/ml, 4.61±1.28ng/ml and 4.79±1.21 ng/ml in 8 μg, 12 μg and 16 μg groups, respectively).These results demonstrated that GnRH injection at a dose of 12 μg is optimal to maximize the libido and semen quality of pubertal buffalo bulls.