The genes coding for the insulin-like growth factor-1 receptor (IGF1R) and a porcine endothelium-derived 21-residue vasoconstrictor peptide (EDN) were localized in the pig by means of radioactive in situ hybridization. IGF1R was mapped to chromosome region 1q1.7-->q2.1 and EDN to 7p1.3-->p1.2. The results are discussed in relation to the position of their homologous loci in man.