We have previously studied mouse Cdv (carnitine deficiency-associated gene expressed in ventricle)-1 related gene Cdv-1IR and its human counterpart CDV-1R, and revealed that mouse Cdv-1R was predominantly expressed in testis by multiple tissue northern analysis. To further localize the Cdv-1R mRNA in mouse testis and epididymis tissue, in situ hybridization study was reported in this article. In the adult mice, the Cdv-1R expression was intensively found in the epithelial cells of the caput and corpus epididymis, whereas it was moderately detected in the initial segment, and weakly in the cauda epididymis. In the seminiferous tubles of the testis, no obvious hybridization signals were observed above the background level. This Cdv-1R region-specific expression pattern in the epididimis suggests Cdv-1R may play an important role in sperm maturation. Moreover, considering the Cdv-1R has a similar expression distribution in epididymis to the OCTN2, it would appear that Cdv-1R might be involved in the carnitine pathway in the epididimis.