Résumé : Summary. A linkage relationship has been detected between the bovine plasma protease inhibitor 2 (Pi‐2) and S blood group loci by linkage study within a single pedigree. Using the sequential lodscore test, the recombination fraction (δ) with maximum likelihood has been estimated at 0.200 ± 0.043, with a maximum lodscore value of 3.466 at δ= 0.200. © 1987 International Society for Animal Genetics