A novel human zinc finger gene, ZNF300, was isolated from human embryos on the base of the enrichment of C2H2-specific mRNAs. The ZNF300 cDNA is 3104 bp long and encodes a 604-amino acid protein with an amino-terminal KRAB domain, and 12 carboxyl-terminal C2H2 zinc finger motifs. According to the genome database, ZNF300 is assigned to chromosome 5q33.1. Northern blot analysis revealed that the ZNF300 transcripts are expressed mostly in heart, skeletal muscle and brain. ZNF300 is localized to the nucleus and the KRAB domain of ZNF300 protein exhibits transcription repressor activity. These results suggest that ZNF300 is a ubiquitous transcription repressor in the nucleus.