The mouse Peg1/Mest gene is an imprinted gene that is expressed particularly in mesodermal tissues in early embryonic stages. It was the most abundant imprinted gene among eight paternally expressed genes (Peg 1-8) isolated by a subtraction-hybridization method from a mouse embryonal cDNA library. It has been mapped to proximal mouse chromosome 6, maternal duplication of which causes early embryonic lethality. The human chromosomal region that shares syntenic homology with this is 7q21-qter, and human maternal uniparental disomy 7 (UPD 7) causes apparent growth deficiency and slight morphological abnormalities. Therefore, at least one paternally expressed imprinted gene seems to be present in this region. In this report, we demonstrate that human PEG1/MEST is an imprinted gene expressed from a paternal allele and located on chromosome 7q31-34, near D7S649. It is the first imprinted gene mapped to human chromosome 7 and a candidate for a gene responsible for primordial growth retardation including Silver-Russell syndrome (SRS).