Changing physician behaviour has become an important focus of medicine over the past two decades.1-3 The rapid expansion of medical knowledge and concerns about quality of care, have led to the birth of both the practice guideline movement4 ,5 and evidence based medicine.6 ,7More recently, medical informatics and patient participation in care have matured as distinct clinical and research entities.8-11 Great Britain has recognised the importance of improving the quality of health care with the creation of the National Institute of Clinical Excellence and the Commission for Health Improvement.2 Ultimately, each of these developments hopes to influence physician behaviour and affect how physicians make decisions on behalf of patients.

Rather than a traditional review of a medical topic, we have chosen to focus on a few selected issues that are critical if we are to understand how to change physician behaviour. This paper has four parts. Firstly, we briefly review issues related to quality of care to set a context for the need to change physician decision making as a key step to improvements in quality. Secondly, we present a contemporary view of how physicians make decisions. Thirdly, we summarise what is known about changing physician behaviour. Finally, we conclude with our own views about the topic. Our focus is on ambulatory care rather than inpatient services, although many of our comments are relevant to decision making in either environment.