The Black Bengal bucks of Indian sub-continent generally show a noted seasonal variation during in reproductive activity. India has a good number of Black Bengal goat populations, which has an important role in the lives of the goat rearers. The objective of thepresent study is to comprehendthe influence of seasonal variation on the testosterone hormone of Black Bengal bucks(Capra aegagrus hircus) in two different agro-climatic zones in India. The highest mean value oftemperature (42.6 ± 1.5 ºC) has been reported during the month of April or May in the season of pre-monsoon in Purulia. However, the lowest value of temperature (8.6 ± 0.9 ºC) has been reported during the month ofDecember or January in the season of post-monsoon again in Purulia.Serum testosterone was analyzed in blood samples collected once a week. It has been observed that, from January to April for both of the regions of Purulia and Nadia and the month May has the lowest serum testosterone level in Purulia (1.22 ± 0.18 ng/ml) and the serum testosterone levels stayed approximately the same from January to March in Purulia and more or less similar in Nadia.However, the serum testosterone level reached to its peak level in November in both the region Nadia (8.79 ± 1.3 ng/ml) and Purulia (6.59 ± 0.41ng/ml) respectively. It can also be presume thatthe early periods of the post-monsoon season can be taken as an alternate breeding seasons for Black Bengal breeds.