The aim of this research is to assess the benefits, risks, and 'value for money' of exercise referral schemes for people with an established medical condition, such as heart disease, stroke or osteoporosis. Evidence from previously conducted studies will be found by systematically searching the research literature, collating the results in a standard format and an overview of the findings produced. The differing effects identified will be related to the resources used (such as the time of practice nurse assessing the suitability of patients and the time exercise specialist providing the exercise), and compared using health economics and decision analysis methods. We hope to identify which patients benefit most from exercise referral schemes and also to identify areas where future research is required.