Abstract
The Es-6 locus is assigned to linkage group vII of the rat, which consists of three loci, coding for a morphological trait, a histocompatibility antigen and an isozyme polymorphism. The linkage between Es-6 and the lx locus seems to confirm the previously suggested homology between Es-6 and the mouse Es-17 locus and may indicate homology between lx and the mouse lu locus.