ABSTRACT: OBJECTIVES: To determine the use of antibiotics by primary care doctors. METHODS: General practitioners in Hong Kong were invited to fill in a short questionnaire on every patient with infection that they had seen on the first full working day once every three months for four consecutive quarters starting from December 2005. RESULTS: Forty six primary care doctors took part and a total of 3096 completed questionnaires were returned. The top three diagnoses were upper respiratory tract infection (46.7%), gastrointestinal infection (8.2%) and pharyngitis (7.1%). Thirty percent of patient encounters with infections were prescribed antibiotics but only 5.2% of patient encounters with upper respiratory tract infection (URTI) were prescribed antibiotics. Amino-penicillins were the most commonly used antibiotics while beta-lactam/beta-lactamase inhibitor combinations (BLBLIs) were the second most commonly used antibiotics and they accounted for 16.5% and 14.0% of all antibiotics used respectively. Of all patients or their carers, those who demanded or wished for antibiotics were far more likely to be prescribed antibiotics (Pearson chi-square test, p < 0.0001). Those patients who were attending the doctors for follow-up consultations were also more likely to be prescribed antibiotics (Pearson chi-square test, p < 0.001). CONCLUSION: The antibiotic prescribing patterns of primary care doctors in Hong Kong are broadly similar to primary care doctors in other developed countries but a relatively low rate of antibiotics is used for URTI.