A rat brain cDNA probe was used to localize a gene encoding the alpha 1 subunit of neuronal dihydropyridine-sensitive L-type calcium channels in the mouse and human genomes. Hybridization of the probe to Southern blots made with DNAs from a Chinese hamster x mouse somatic cell hybrid panel indicated that this gene maps to mouse chromosome 14 (Chr 14). Southern blot analysis of an intersubspecies cross demonstrated that the calcium channel alpha 1 subunit gene, termed Cchl1a2, can be positioned 7.5 cM proximal to Np-1. Similarly, segregation among human X rodent somatic cell hybrids indicated that CCHL1A2 maps to human chromosome 3. These assignments are consistent with a region of linkage homology between human chromosome 3p and a proximal region of mouse Chr 14.