Asymmetric transport of mRNA within the cells is mediated by RNA-binding proteins that form, along with the mRNAs and perhaps other small RNAs, stable ribonucleoprotein complexes. However, the nature of the protein components of these complexes in vertebrates is still unknown. In Drosophila, genetic studies have identified a number of potential genes that are necessary for localization of mRNAs in oocytes; one of the most studied is the staufen gene. The staufen protein has been shown to bind to localized mRNAs in oocytes and to be expressed in somatic cells as well. To understand the mechanism of mRNA transport in mammals and characterize its components, we recently cloned and sequenced the human staufen homolog cDNA (HGMW-approved symbol STAU). In this paper, we show that the gene is unique in the human genome and report its chromosomal localization by fluorescence in situ hybridization. The human staufen gene maps to chromosome 20q13.1, a region that is associated with certain genetic diseases.