The prescribing behaviour of family doctors in Hong Kong towards upper respiratory tract infections (URTIs), and the major clinical factors that might affect such behaviour, were studied. Members of the Hong Kong College of Family Physicians were surveyed; 801 completed the questionnaire with an overall response rate of 65%. Purulent nasal discharge, purulent sputum, persistent fever over three days, patients looking unwell, exudates on throat, inflamed eardrums and cervical lymphadenopathy made more than half the respondents 'likely' or 'very likely' to prescribe antibiotics. Those in private practice and those who graduated in Hong Kong were more likely to prescribe antibiotics, while fellows of the College were less likely to do so. Vocational training and higher qualifications in family medicine/general practice, however, revealed minimal effect. Our results showed that many doctors are still prescribing antibiotics when they encounter URTI patients presenting with clinical factors that have been proven to have no or little benefit from antibiotics.