A number of serious hereditary disorders are now known to be associated with defective expression of collagen genes, and these findings have underscored the important and varied roles that the collagen family of genes must play during normal mammalian development. Although the activities of genes encoding the quantitatively major types of collagen are fairly well characterized, functions of the many minor types of collagen remain a matter of speculation. As a first step toward a functional analysis of type XI collagen, a member of this class of poorly understand "minor" collagen proteins which is expressed primarily in hyaline cartilage, we have used human probes for the gene encoding the protein's alpha 2-subunit (COL11A2) to isolate and map homologous murine DNA sequences. Our results demonstrate that Col11a-2 is embedded within the major histocompatibility complex (MHC), within 8.4 kb of the class II pseudogene locus, Pb, and confirm that human and murine alpha 2(XI) collagen genes are located in very similar genomic environments. The conserved location of these genes raises the possibility that type XI collagen genes may contribute to one or more of the diverse hereditary disorders known to be linked to the MHC in mouse and human.