We reported the identification of a novel gene termed TDRP (encoding testis development-related protein) that might be involved in spermatogenesis. The human TDRP gene had two distinct transcripts, TDRP1 and TDRP2, which encoded proteins of 183 aa and 198 aa respectively. Tdrp mRNA was predominantly expressed in testis tissue. We generated rabbit polyclonal antibodies specific against human TDRP1. Immunohistochemistry analysis showed TDRP1 was expressed in spermatogenic cells, especially with high expression in spermatocytes. We provided evidence that TDRP1 distributed in both cytoplasm and nuclei of spermatogenic cells. Expression patterns of Tdrp1 mRNA and its protein were investigated in the rat testis tissues of different developmental stages. Both Tdrp1 mRNA and its protein were barely detected in the testis of neonatal rats, increased remarkably at 3 weeks postpartum, and peaked at 2 months postpartum. We also investigated TDRP1 expressions in testis tissues of azoospermic men with defective spermatogenesis. Western blot analysis showed that TDRP1 expressions were significantly lower in the testis tissues of azoospermic men compared with normal controls. These current data demonstrated that as a nuclear factor, TDRP1 might play an important role in spermatogenesis.