A 280 kilobase (kb) contig was isolated from mouse genomic P1 and cosmid libraries, using as probes human cDNA and genomic DNA fragments that map in the interval between the second component of complement and tumor necrosis factor genes of the HLA complex. The clone contig demonstrates synteny of eleven mouse genes that are homologous to genes initially mapped within the human major histocompatibility complex. These include the mouse homologs of BAT2 (HLA-B-associated transcript 2) through BAT9 and also three HSP70-related genes. Five P1 clones form a contig of 240 kb that spans from BAT9 through BAT3. Twelve cosmid clones are arranged in three contigs that confirm most of the structure of the P1 contig and link the mouse BAT3 homolog to the BAT2 homolog approximately 15 kb farther telomeric. Polymorphic DNA markers within the cloned region were used to map the cleft palate susceptibility-1 (Cps-1) locus to the interval between Hsp70.1 and BAT6 (valyltRNA synthetase). This refines the location of the Cps-1 locus to a 45 kb region contained in the H2-124 P1 insert. © 1994 Springer-Verlag.