The Na+/H+ exchangers (NHEs) catalyze the transport of Na+ in exchange for H+ across membranes in organisms and are required for numerous physiological processes. Here we report the cloning and characterization of a novel human NHEDC1 (Na+/H+ exchanger like domain containing 1) gene, which was mapped to human chromosome 4p24. This cDNA is 1859 bp in length, encoding a putative protein of 515 amino acids. The NHEDC1 proteins are highly conserved in mammals including human, mouse, rat, and Macaca fascicularis. One remarkable characteristic of human NHEDC1 gene is that it is exclusively expressed in the testis by RT-PCR analysis. Western blot analysis showed that the molecular weight of NHEDC1 is about 56 KDa.