STARTVAC® (HIPRA) is a polyvalent mastitis vaccine, directed against both enterobacterial and staphylococcal species, that has been registered for use in the European Union and in many other countries worldwide. The STARTVAC® formulation is based in the inactivated Escherichia coli J5 strain and a Staphylococcus aureus bacteria containing the exopolysaccharide Poly-N-acetyl β-1,6 glucosamine (PNAG) involved the biofilm phenotype of the bacteria. The objective of this study was to analyse the reactivity of the antibodies induced by the STARTVAC® vaccine against S. aureus and E. coli bovine mastitis isolates from different areas of Japan and Europe.