In 100 matings grouped in 83 pedigrees linkage analysis has been performed for the relation of PGMX and PGM3 to sex and several marker loci including PTC, ABO, Rh, MNS, P, K, Le (= Se), Lu, Fy, Hp, Gc, Gm, Inv, AcP, ADA, AK and HL-A. Lod scores calculated by other authors have been included in the final evaluation. For the PGM3:HL-A relation the probability of linkage is raised from 0.054 to 0.25, while the probability is raised only slightly for PGM3:P and PGM3:K relations, i.e. to 0.073 and 0.060, respectively. For the PGM^Fy relation, the probability is unchanged. For the rest of the relations investigated, the evidence disfavours linkage. Unfortunately, the phenotyping of the PTC-taste sensitivity and the Lu(a) character must be regarded with some scepticism. The previously reported excess of Hp 2–1 children in the mating Hp 2–1 × Hp 2–2 was also found in this series. In the present material the gene frequency of AK2 is 0.033, and the gene frequency of ADA2 is