SUMMARYWe established the organization of the AKR Qa region and determined the sequence of the 44 and Q5 genes. Restriction mapping and genomic Southern blot analysis revealed that the AKR strain codes for only three H‐2K homologous genes in this region. The AKR Q5 gene is not homologous to the Q5 gene of the C57BL strain, but is presumably allelic to the Q5 gene isolated from Balb/c. The organization and structure of the AKR Qa family is virtually identical to the Qa genes of the C3H mouse. The AKR Q5 gene, in contrast to other H‐2K homologous Qa region genes, codes for a typical transmembrane region, and upon transfection into BHK cells, a 1.6 kb Q5 transcript is detec