Partial complementary DNAs for the epsilon 1, epsilon 3 and zeta 1 subunits of the human N-methyl-D-aspartate (NMDA) receptor channel were cloned using the corresponding mouse subunit cDNA clones as probes. Genomic DNA clones for the human epsilon 1, epsilon 3 and zeta 1 subunit genes were isolated using the corresponding partial cDNA clones as probes. By the fluorescence in situ hybridization, we mapped the genes for the epsilon 1, epsilon 3 and zeta 1 subunits of the human NMDA receptor channel to chromosomes 16p13, 17q25 and 9q34, respectively.