Data on the linkage relationships of HL-A with 31 autosomal genetic markers are presented. Among 40 markers for which some information on the linkage relationship with HL-A is available, four (PGM3, GBG, Ch and Pg) have lod scores > +3. The most likely order for the polymorphic systems tentatively assigned to chromosome 6 is Kell: Pg: (HL-AGBG): Ch: PGM3: P.