Mastitis is the most “antibiotic consuming” pathology in dairy medicine. Though antibiotics and antibiograms are known to vets since the early fifties, our practices did not evolved a lot from empiric antibiotic therapy. Indeed, the need for a treatment, the cost and the delay for an antibiogram are most of the time incoherent with a routine practice. Nevertheless, there is a surge for rational use of antibiotics. Our study was based on 1100 mastitis events from 30 Belgian farms collected between January 2011 and June 2012. We chose to compare tissular cure (TC) based on the threshold of 200.000 somatic cells/ml in milk at milk control at least 60 days after the clinical mastitis event. Regarding the mastitis event, severity (according 3 grades: alteration of milk as grade 1, alteration of quarter as grade 2 and alteration of general state as grade 3), quarter, treatments were recorded. We also assessed a chronicity status based on previous somatic cell count (SCC) of the cow. It was considered a new case a cow which at least 15 days before had an SCC <200.000 cells/ml, other were marked as chronic cases. In our distribution, we see a seasonal rise of incidence between January and May. This period would represent twice as many mastitis as the summer period. Overall TC reaches 46% of all mastitis events, which is quite poor. Rear quarters had significantly lower TC (p<0,05%). Grade 3 mastitis had lower TC, 42,6% (p<0.05%) versus 48,9 % for grade 2 and 44,2% for grade 1. Almost 49% of all mastitis was considered as chronic cases, which TC was 33% on average, whereas new cases reached 55,3% TC. Study of treatment was frustrating given the high number of different combinations of treatments. It was underlined that 4th generation cephalosporins (C4G) were the most used in our cohort, followed by aminopenicillin/methicillin association (PENA/PENM) and 1st generation cephalosporins/aminoglycosids (C1G/AG) association. Of these intramammary treatments, 20% of the cases were submitted to a second intramammary ...