Variation in adherence to clinical guidelines, and in the organisation and delivery of health care significantly impact patient outcomes and health service costs. Despite mounting evidence of variation in clinical practice, the funds allocated to improve the quality of existing services remain small, relative to the resources allocated to new technologies. Quality improvement is a complex intervention, with a lack of focus on outcomes, and greater uncertainty around its effects. These factors have contributed to a relatively narrow, mainstream view of quality improvement as focussing on safety, with efforts to improve adherence to best practice limited to high profile clinical areas. This paper presents an analysis of linked, routinely collected data to identify variation in patient outcomes and processes of care across hospitals for patients presenting with low-risk chest pain. Such analyses provide a low cost, broadly applicable approach to identifying potentially important areas of variation in clinical practice, to inform the prioritisation of more detailed analyses to validate, and further investigate the causes of variation.