Beginning from a mouse EST (GenBank accession No. BE644537) which was significantly up-regulated in cryptorchidism and represented a novel gene, we cloned a new gene (GenBank accessionNo. AY138810) which is related to apoptosis in human spermatogenic cells by means of GeneScan programand PCR technology. The gene whose full cDNA length is 1875 bp containing 8 exons and 7 introns islocated in human chromosome lq13.3. Its protein containing 316 amino acid residues is a new member ofHSP40 protein family because the sequence contains the highly conserved J domain which is present in allDna J-like proteins and is considered to have a critical role in DnaJ-DnaK protein-protein interactions. TSARG6protein displays a 45% identity in a 348-amino acid overlap with DJB5_HUMAN protein. The result ofRT-PCR and Northe blot analysis showed that TSARG6 is specifically expressed in adult testis and thetranscript is 1.8 kb. Based upon all these observations, it is considered that we cloned a new gene whichprobably inhibited human testis spermatogenesis apoptosis.