OBJECTIVES: Community Acquired Pneumonia (CAP) is a major cause of mortality and healthcare resource use worldwide. Proper management of less severe outpatient CAP has demonstrated resource savings without adverse patient outcomes. Although treatment guidelines recommend the use of certain pharmacological agents such as macrolides, fluoroquinolines or doxycycline for outpatient CAP, limited data are available on actual usage. We aim to describe current antibiotic prescribing patterns using a large prescription database. METHODS: The study population comprised IMS MediPlus-UK. Adult CAP outpatients (ICD-10: J13-J15) diagnosed during January 1, 1997 through December 31, 2001 and treated with antibiotics were included. Patients were followed through the initial duration of therapy and an additional 4-week period to capture the original therapy and added antibiotic use. Those with HIV/AIDS were excluded. Antibiotics were categorized as "penicillins", "cephalosporins", "macrolides", "tetracyclines", "quinolones", and "other" (including multisubstance and trimethoprim). RESULTS: Among 739 episodes identified, most were initially treated by penicillin group (including amoxicillin, ampicillin, penicillin,41%), and macrolides (erythromycin, azithromycin, clarithromyc,28%). Cephalosporins, tetracyclines, and quinolones were used less often, 10%, 4% and 5%, respectively. The median prescribed length of therapy was 7 days, except tetracyclines (6). The means (days)(standard deviation) were: 6.9(2.8)for penicillins, 7.4(1.9)for cephalosporins, 9.5(17.2) for macrolides, 6.3(2.5) for tetracyclines, 6.4(1.5) for quinolones, and 6.7 (1.5)for other. The percentage of patients received a second antibiotic during study period ranged from 15% to 23%, with the second round mostly in the same category as the initial antibiotic. CONCLUSIONS:Duration of therapy for CAP outpatients remains relatively long in this UK population. A substantial proportion of patients received additional therapy during the episode of care. Long therapy duration has been associated with patient nonadherence, and/or treatment failure. Effective therapy options with shorter length of therapy are needed to improve CAP outpatient management and patient outcomes.