Abstract: Reproduction of goat bucks in the semi-arid area under the semi-extensive system often receives little attention. This study aimed to investigate the effect of goat bucks breeds (Mountain Black, Damascus and Mountain Black-Damascus hybrid) and different months of breeding season on Testosterone concentrations after gonadotropin releasing hormone stimulations. Five from each of bucks (Mountain Black, Damascus and Mountain Black- Damascus hybrid) were used. All of the bucks met the minimum requirements of breeding soundness exam. Testosterone concentrations in response to exogenous gonadotropin releasing hormone stimulations were investigated. Results indicated that there were no significant differences in testosterone concentrations and folds due to breed and months of the breeding season. However, there was a tendency for significant differences (p<0.1) between breeds and stages of the breeding season for scrotal circumference. Moreover, there was a positive correlation between scrotal circumference and testosterone folds for all the bucks (r = 0.1; p<0.05). In conclusion, testosterone secretions under gonadotropin releasing hormone stimulations were not different among breeds of goat bucks and months of their breeding season in the semi-extensive grazing system. Thus, libido was not improved during months of breeding season of the bucks.