SUMMARYSingle pair matings were performed to confirm the genetic basis of electrophoretic variants of several enzyme systems in north-east Atlantic herring (Clupea harengus) collected in spawning condition from the North Irish Sea. Mendelian inheritance of codominant autosomal alleles was established for Aat-2, Idh-2, Ldh-2 and Pgi. Crosses among Fum-1, Idh-1 and Sod homozygotes produced only homozygous offspring.This study also permitted the investigation of linkage relationships between polymorphic loci. Linkage was not observed between any two loci in the 13 pairwise comparisons made. This analysis constituted the first investigation of linkage relationships in the species.