A manuscript entitled “Genetic polymorphisms among C57BL/6 mouse inbred strains” has been just published by Esther Zurita, Mónica Chagoyen, Marta Cantero, Rosario Alonso, Anna González-Neira, Alejandro López-Jiménez, José Antonio López-Moreno, Carlisle P. Landel, Javier Benítez, Florencio Pazos and Lluís Montoliu in Transgenic Research. The Illumina® Mouse Medium Density Linkage Mapping panel, with 1,449 single nucleotide polymorphisms (SNPs), was used to genotype individuals from ten C57BL/6-related strains: C57BL/6JArc, C57BL/6J from The Jackson Lab, C57BL/6J from Crl, C57BL6/JRccHsd, C57BL/6JOlaHsd, C57BL/6JBomTac, B6(Cg)-Tyr (<c-2j>)/J, C57BL/6NCrl, C57BL/6NHsd and C57BL/6NTac. Twelve SNPs were found informative to discriminate between the “/N” and “/J” C57BL/6 mouse substrains considered. These results will be instrumental for the correct genetic monitoring and appropriate mouse colony handling of different transgenic and knockout mice produced in distinct C57BL/6 inbred substrains. The SNP raw data are also available from the Mouse Phenome Database at Jackson Laboratory.