Linkage relations between pepsinogen Pg5 and 28 genetic marker loci have been analyzed in Norwegian families. No strong hint of linkage was found. Linkage to Pg5 in males has been ruled out below 25% recombination for HLA and GPT, below 20% recombination for Rh, PGM1, ACP, Gc, MNSs, PGM3, and Gm and Pi, below 15% recombination for Hp, below 10% recombination for Fy, ABO, C3 and Jk and below 4% for Kell, Tf, C6, Km and Le(Se). Possibilities of loose linkages include Pg5-C6 and Pg5-MNSs, both of which should be followed up.