SummaryThree biochemical gene markers test the hypothesis that the European hake,Merluccius merluccius(L.), along the west European continental shelf are one race. The three polymorphic loci were serum transferrin (Tf), eye vitreous fluid butyric esterase (Es) and liver superoxide dismutase (Sod). Five transferrin alleles, three esterase alleles and two superoxide dismutase alleles were identified. Heterogeneity tests on genotype frequency distribution for twelve areas ranging from Norway to Biscay revealed no significant variation. The results using these genetic tags are consistent with the unit race hypothesis for hake throughout the sea areas sampled.