We have cloned a gene, ZFF29 (zinc-finger protein of human fetal liver erythroid cells 29), from human fetal liver erythroid cells. Two types of mature mRNA were identified and designated ZFF29a and ZFF29b. In human genome the ZFF29 gene is on chromosome 9q, and the two forms are splice variants. There is a unique transcription start site, which predicts major mRNAs composed of 2485 bases for ZFF29a and 1801 bases for ZFF29b. The anticipated mRNAs were demonstrated in K562 cells, but not in any adult human tissues examined by Northern blotting. In the mouse, reverse transcription-PCR revealed that the ZFF29 mRNA is present in adult bone marrow and ovary at a higher level than in any other tissues examined. These findings suggest that ZFF29 proteins are expressed in embryonic/fetal erythroid tissues. The deduced polypeptide chains of ZFF29a and ZFF29b are composed of 306 and 350 amino acids respectively. A unique zinc-finger motif composed of two contiguous Cys(2)His(2)-type fingers is common to both forms of ZFF29. They are nuclear proteins and ZFF29b, but not ZFF29a, is an activator of erythroid gene promoters.