BACKGROUND: Treatment for respiratory tract infections (RTI) in the primary care setting is empirical. Antibiotic prescribing patterns differ among countries and are based on the prevalence of antibiotic resistance in the geographical area. The aim of this study was to compare the antibiotics prescribed by general practitioners (GPs) for RTIs between Spain and Denmark. METHODS: Observational multicenter survey carried out in the primary healthcare setting. Two groups of GPs in Spain and Denmark recorded all contacts with RTI patients during a 3-week period between November 2001 and January 2002. RESULTS: A total of 2833 RTI cases were registered. Broad-spectrum penicillins and combinations of these drugs plus beta-lactamase inhibitors were the antibiotics most frequently prescribed by Spanish GPs (62.3%), followed by macrolides (22.3%). In contrast, narrow-spectrum penicillins were most commonly prescribed by Danish GPs (58% of all prescriptions), followed by macrolides (29%) (P < .001). Antibiotics most frequently prescribed for ear, tonsillar, sinus and bronchopulmonary infections were broad-spectrum penicillins among Spanish GPs and narrow-spectrum penicillins in Denmark. Spanish GPs prescribed penicillin V only for tonsillitis, accounting for 5.1% of the antibiotics used for this condition, whereas this drug accounted for 91.7% of the prescriptions by their Danish colleagues for the same indication. CONCLUSIONS: The substantial differences in RTI management between the participating GPs should make us reflect on the rational use of antibiotics. The discrepancies disclosed may indicate dissimilarities in recommendations, traditions, habits, or antibiotic pressures between the countries studied.