The antibiotic component of the 2006 national survey on the prevalence of nosocomial infections aimed to describe the antibiotics prescribed in healthcare facilities. Conducted on a specific day in June according to a standardized protocol, the survey included all inpatients; antibiotics were recorded according to the ATC5 classification. Of the 358,353 patients included (2,337 HC), 55,624 (15.5%) received treatment for a total of 74,515 antibiotics. The prevalence of treated patients (PpATB) was higher in short-stay care (24.8%), particularly in intensive care (49.0%), than in follow-up care and rehabilitation (SSR, 9.9%) or long-term care (SLD, 4.3%). It varied by indication: community-acquired infection (7.4%), nosocomial infection (NI, 3.9%), surgical antibiotic prophylaxis (2.4%), prophylaxis of opportunistic infections (1.3%), or multiple indications (0.5%). The most commonly prescribed drugs were amoxicillin-clavulanic acid, ofloxacin, amoxicillin, ceftriaxone, and ciprofloxacin. From 2001 to 2006, the PpATB changed little (16.4% vs. 16.7%) among the 1,351 healthcare facilities that participated in both surveys. It increased in intensive care units but decreased in obstetrics, post-surgical care, long-term care, and psychiatry. It decreased for hospital-acquired infections or prophylaxis and showed contrasting trends by age for community-acquired infections. Strengthened efforts to preserve antibiotic efficacy in hospitals are necessary. (R.A.)