We report here—using northern experiments, western blotting, and immunohistochemistry—on the findings that the plasma type glutathione peroxidase, GPx3, a major enzyme in reducing lipid hydroperoxides and hydrogen peroxide in plasma, is also expressed at significant levels in tissues of the male genital tract including epididymis and vas deferens. Within the epididymis and the kidney, the accumulation of the GPx3 mRNA and protein were investigated during postnatal development and found to be temporally regulated in a tissue‐specific manner. Furthermore, we show here that androgen withdrawal by castration down regulates the expression of the GPx3 gene both in the epididymis and vas deferens while GPx3 expression in the kidney was found to be androgen‐independent. Finally, immunohistochemistry data reveals that within the epididymis GPx3 distribution is quite peculiar suggesting the existence in this organ of complex traductional and/or transcriptional regulatory processes. Mol. Reprod. Dev. 51:362–372, 1998. © 1998 Wiley‐Liss, Inc.