This study aimed to evaluate the effect of ginger extract (GIN) on reproductive performance of buffalo bulls. Sub-fertile buffalo bulls (n=8) with body weight ranging from 400-450 kg and 22-25 mo of age were divided into two groups (n=4 in each). The 1^st group was fed on the basal diet without treatment, but the basal diet was spread with 10 ml distilled water and served as a control. Bulls in the 2^nd group were fed the basal diet spread with liquid GIN extract (200 mg GIN dissolved in 100 ml/kg diet) for 4 mo (2 mo as a preliminary period and 2 mo as a collection semen period. Semen was collected twice/week for 8 weeks. Blood samples were taken at the end of experiment. Results showed that GIN improved ejaculate volume, motility types, vitality, membrane integrity, concentration and total sperm output, while decreased (P<0.001) reaction time, and acrosomal damage. Also, GIN increased (P<0.001) testosterone by 103.7%, RBCs, PCV, and hemoglobin, while decreased WBCs count (P<0.01). Plasma concentration of total proteins, albumin, globulin significantly increased, while urea and creatinine decreased (P<0.001). Enzyme activity of AST and ALT significantly decreased in GIN group. Oral dose of 200 mg ginger in 100 ml distilled water/kg diet improved sexual activity and semen quality of buffalo bulls with low reproductive efficiency.