BACKGROUND: General practitioners in the UK play a key role in prevention but provision of preventive services is variable. The 2004 General Medical Services contract allows Primary Care Trusts (PCTs) to address health needs through providing locally agreed payments for Local Enhanced Services (LESs). This study identifies how this contractual flexibility is used for preventive services and explores its perceived effectiveness. METHODS: Semi-structured interviews were carried out (2008-09) in 10 purposively selected case study sites in England. Details of LESs for these sites were collected (2009) through Freedom of Information requests or local contacts. A national on-line survey of PCTs (2009) provided a national context for case study findings. RESULTS: LESs were considered to be effective in incentivizing preventive activity. However, specifications and performance management were often weak, awareness of how to optimize incentives was low and, as optional services, LESs were perceived to be at risk in a financial downturn. CONCLUSIONS: Using LESs for preventive services highlights gaps in 'core' primary care responsibilities and in the national pay-for-performance framework. Current incentive arrangements are complex, could increase inequalities and provide only a partial, short-term solution to developing a proactive approach to prevention in primary care.