International audience; Introduction: Antibiotic resistance and reduction of antibiotic use are main issues in pork production. In collaboration with vet practicioners in charge of health management, a french producer organization initiated an « antibiotic-free » production chain in June 2014. Farmers that signed the adhesion contract had to raise pigs without administering antibiotics from birth to slaughter. Materials and Methods: The 29 farms that were part of this production chain were included in the study. Those farms are located in the Normandy region, West of France. The producer organization provided the technical parameters to estimate animal populations to which antibiotics could have been given. Vet practicioners gave access to the lists of drug sales. A questionnaire was performed to precisely the antibiotic use pattern in each farm. Two different six-month periods were selected for the data collection: August 1st, 2013 to January 31th, 2014 (P1) and November 1st, 2014 to April 30th, 2015 (P2). These periods were situated before (P1) and after (P2) the inclusion in the antibiotic-free protocol respectively. The use of antibiotics is expressed in weight, nDD/animal (number of Daily Dose) and nCD/animal (number of Course Dose). Results: Twenty-five farmers accepted to participate and the herds of the sample were similar to the french pig herds on average in terms of size and technical performances. The total amount of anitibiotics used in the farms of the sample decreased by 64.2% between P1 and P2. In five farms, antibiotic consumption increased because of occurrence of acute health disorders. All physiological stages underwent a decrease of both nCD and nDD/animal values between P1 and P2. For weaners, nDD/animal and nCD/animal decreased by 85 and 79% respectively. The oral route was predominant in P1 but this administration way exhibited the most important decrease. The sharp decline in the consumption of oral antibiotics indicates that there was no substitution of medicated feed by antibiotics via drinking water. The number of treatments by injections slightly increased between the two periods. In our sample, antibiotic use could be significantly reduced for weaners whereas and it was more difficult during the lactating period partly because of arthritis. Conclusion: The establishment of an antibiotic-free production chain has led to a significant reduction in the use of antibiotics in most farms, except when disease outbreaks occured. It should be noted however that this producer organization benefits from a favourable sanitary status resulting from a dynamic health policy for several years (all herds are PRRS free and some are also Mycoplasma hyopneumoniae free)