26Methicillin-resistant Staphylococcus aureus (MRSA) is infrequently reported in mastitis. Yet, 27 as in many other countries, the prevalence of methicillin resistance among S. aureus from 28 mastitis is currently unknown in Belgium. 29To elucidate this, the presence of mecA was investigated in 118 S. aureus strains originating 30 from diagnostic mastitis milk samples from 118 different farms experiencing S. aureus 31 mastitis. MRSA strains were characterized by disk diffusion susceptibility testing, spa-typing, 32MLST and SCCmec-typing. In an additional study, four MRSA-positive farms were selected 33 to assess the in-herd prevalence of MRSA, by sampling all cows in lactation. Isolated MRSA 34 strains were similarly characterized. 35The mecA gene was detected in eleven (9.3%) of the 118 S. aureus isolates, indicating that 36 nearly 10% of the Belgian farms suffering from S. aureus mastitis have an MRSA problem. 37The in-herd prevalence varied between 0% and 7.4%. Characterization of the MRSA strains 38showed that they were all resistant to tetracycline. Additional resistances to macrolides, 39 lincosamides and aminoglycosides were frequently detected. The strains were ST398, spa-40