A cDNA encoding the complete reading frame of a novel homeodomain-containing protein, named zhx-1, has been cloned from a mouse bone marrow stromal cell line. The ORF encodes a protein of 873 amino acids, in which two C2-H2 zinc-fingers and five homeodomains have been identified. These features classify zhx-1 as a member of the ZF class of homeodomain transcription factors, zhx-1 mRNA is widely expressed in adult mouse, although it is preferentially expressed in brain. At least, two homologous mRNAs are present in humans suggesting that zhx-1 is the first member of a novel subclass of homeodomain factors.