Type XIII collagen is a recently described collagen that resembles in structure the short-chain collagens of types IX, X, and XII. Unlike any other collagen, the type XIII is found in several different forms generated through alternative splicing. A 2.0-kb genomic fragment from the human alpha 1 (XIII) collagen gene was isolated and shown by DNA sequencing to contain exon 12 as counted from the 3' end. This fragment was used as a probe to localize the gene. The gene (COL13A1) was assigned to chromosome 10 by hybridization of the probe to DNA isolated from a panel of human-mouse somatic cell hybrids containing different human chromosomes. Furthermore, the gene was mapped to the q22 region by in situ hybridization to metaphase chromosomes.