The European Surveillance of Antimicrobial Consumption (ESAC) project collects data on antibacterial use in Europe, applying the Anatomic Therapeutic Chemical classification system and defined daily dose methodology, as recommended by the World Health Organization. Comparable data for the United States have been collected from IMS Health. The IMS Health sales data, processed according to ESAC methodology, suggest that outpatient antibacterial use in the United States is high (only 3 of 27 European countries used more) and is mainly characterized by a shift towards newer antibiotics.