The glucose transporter is a membrane glycoprotein that is involved in the uptake of glucose by most, if not all, animal cells. A cloned cDNA that encodes the human protein was used to map the gene to a specific chromosomal region and to identify a DNA polymorphism. The human gene (designated GLUT) was assigned to chromosome 1p31.3----p35 by hybridization of the probe to DNA from a panel of human-mouse somatic cell hybrids containing different human chromosomes and by in situ hybridization to isolated metaphase chromosomes. The most likely location of GLUT is in 1p33. A common two-allele restriction-fragment-length polymorphism was identified with Xba I.