The prescribing behaviour of family doctors in Hong Kong towards upper respiratory tract infections (URTIs) and the factors that might affect such behaviour were studied. All 1016 members of the Hong Kong College of Family Physicians were sent a postal questionnaire. A total of 730 family doctors completed the questionnaire, with an overall response rate of 71.8%. Doctors who were older, more senior, or in private practice were more likely to think antibiotics were useful for URTIs and to prescribe them. These doctors were also more likely to think their patients would expect antibiotics from them. Postgraduate vocational training in general practice/family medicine helped make family doctors think fewer patients would expect antibiotics from them but did not affect their perception of the usefulness of antibiotics for URTIs. Our results showed that doctors with certain characteristics were more likely to prescribe antibiotics for URTIs and these doctors may be targeted for continued medical education.