The chicken insulin-like growth factor 1 gene has been assigned to the short arm of chromosome 1 near the centromere by fluorescence in situ hybridization and genetic linkage analysis. Comparison of physical and genetic linkage maps locates the centromere between the IGF1 and GAPD loci. Comparison of the genetic maps of chicken and other vertebrates reveals a highly conserved syntenic group, including the GAPD-IGF1 loci.