Abstract: The effect of 10% commercial formalin on testicular tissues was evaluated in prepubertal male black Bengal goats. At fifteen days after a single exposure of formalin, testicular atrophy appeared for the first time. At thirty days, the mean weight, length and width of the testes were significantly decreased, compared to those of the control group (*p<0.05). In testes, histopathological changes were not observed uniformly. Peripheral tubules were more affected than central ones. Lesions in all affected seminiferous tubules were not similar. In severely affected areas, the seminiferous tubules collapsed or shrank. While, in some areas, focal or complete necrosis was found. The diameters of the seminiferous tubules were apparently smaller in comparism with that of the control group. Increased connective tissues together with macrophagic infiltration were observed in the interstitial region. Marked eosinophilic staining was also observed in treated testes. It is suggested here that 10% formalin is of advantage for earlier castration in black Bengal goats. Still it is not clear, how this chemical brings about testicular disfunction at prepubertal stage.