Complete cDNA of mouse gene znf230 was cloned by rapid amplification of cDNA ends (RACE). This cDNA is 982 base pairs (bp) in length and encodes a 230 amino acids (aa) protein with a ring finger domain at its C-terminus. Ninety-one and 98% nucleotide (nt) and aa sequence identity are observed with its human homolog. Revealed by Northern blot and reverse transcriptase-polymerase chain reaction (RT-PCR), this cDNA is only detected in testicular tissue, whereas the longer transcripts of 2.4 and 4.4kb are ubiquitously expressed. The expression of znf230 in testis is developmentally regulated and first detected at day 6 postnatal (pn). It reaches adult level between day 14 and 21 pn during which round spermatids appear in seminiferous tubule. The protein of znf230 exhibits DNA binding activity and its ring finger domain may function as an activator module in transcription. Therefore, it is postulated that znf230 may function as a testis specific transcription factor during mouse spermatogenesis.