The N-methyl-D-aspartate (NMDA) receptor channel is essential for synaptic transmission and synaptic plasticity underlying memory, learning, and development. Three subunits of the NMDA receptor channel, NMDAR2A, NMDAR2B, and NMDAR2C (NR2A, NR2B, and NR2C), previously identified in mouse by cDNA cloning and expression, share a high level of homology, although their patterns of expression within the brain may differ. In the present work we report the localization of the gene encoding the human NMDAR2B receptor subunit (called GRIN2B for glutamate receptor, ionotropic, N-methyl-D-aspartate 2B) to chromosome 12p12 by in situ hybridization and somatic cell hybrids.