Background Resistance to antibiotics is a major public-health problem and antibiotic use is being increasingly recognised as the main selective pressure driving this resistance. Our aim was to assess outpatient use of antibiotics and the association with resistance. Methods We investigated outpatient antibiotic use in 26 countries in Europe that provided internationally comparable distribution or reimbursement data, between Jan 1, 1997, and Dec 31, 2002, by calculating the number of defined daily doses (DDD) per 1000 inhabitants per day, according to WHO anatomic therapeutic chemical classification and DDD measurement methodology. We assessed the ecological association between antibiotic use and antibiotic resistance rates using Spearman's correlation coefficients. Findings Prescription of antibiotics in primary care in Europe varied greatly; the highest rate was in France (32.2 DDD per 1000 inhabitants daily) and the lowest was in the Netherlands (10.0 DDD per 1000 inhabitants daily). We noted a shift from the old narrow-spectrum antibiotics to the new broad-spectrum antibiotics. We also recorded striking seasonal fluctuations with heightened winter peaks in countries with high yearly use of antibiotics. We showed higher rates of antibiotic resistance in high consuming countries, probably related to the higher consumption in southern and eastern Europe than in northern Europe. Interpretation These data might provide a useful method for assessing public-health strategies that aim to reduce antibiotic use and resistance levels.