A major role of the peptide hormone somatostatin is inhibition of growth hormone secretion. The effects of somatostatin are mediated through five distinct G-protein-coupled receptors, each of which is expressed in the pituitary gland and other tissues. Allelic variation in the five somatostatin receptor genes (Smstr) could contribute to growth rate and overall body size. To evaluate this hypothesis we determined the chromosomal location of the Smstr genes. Restriction fragment length polymorphisms and single-strand conformational polymorphisms were used to follow the segregation of each gene in interspecific mouse backcrosses. Smstr1 through Smstr5 were localized to mouse chromosomes 12, 11, 15, 2, and 17, respectively. None of the Smstr genes colocalized with single gene mutations that affect growth. However, growth is a quantitative trait influenced by many genes and by the environment. Strains of mice selected for high and low growth have been exploited to identify chromosomal regions that modestly influence growth (J. Cheverud et a1., 1996, Genetics 142: 1305-1319). Several Smstr genes map within these regions, suggesting that they be considered candidate genes for these quantitative trait loci.