Zinc finger (ZNF) proteins play a critical role in cell growth, proliferation, apoptosis, and intracellular signal transduction. In this paper, we cloned and characterized a novel human KRAB-related zinc finger gene, ZNF425, which encodes a protein of 752 amino acids. ZNF425 is strongly expressed in the three month old human embryos and then is almost undetectable in six month old embryos and in adult tissues. An EGFP-ZNF425 fusion protein can be found in both the nucleus and the cytoplasm. ZNF425 appears to act as a transcription repressor. Over-expression of ZNF425 inhibits the transcriptional activities of SRE, AP-1, and SRF. Deletion analysis indicates that the C2H2 domain is the main region responsible for the repression. Our results suggest that the ZNF425 gene is a new transcriptional inhibitor that functions in the MAPK signaling pathway.