BACKGROUND: Lifestyle advice from general practitioners (GPs) has been shown to have a positive effect on population health. In practice, GPs provide lifestyle advice to a minority of their patients only, those who are high risk or already have symptoms. AIM: To look in depth at GPs' attitudes towards adopting a population approach to lifestyle advice and to use these results to identify ways of maximising the potential of GPs to affect population health. METHOD: Thirty-six GPs, purposively sampled by identifying characteristics likely to affect their health promotion activity, participated in a focus group study. Data from the focus groups were transcribed verbatim and analysed using standard methods. RESULTS: The main themes that emerged suggested that GPs do not take a population approach to lifestyle advice because they prefer a high risk approach and doubt their ability to be effective in a population approach. GPs believed that social, cultural, and environmental factors were the most important determinants of population health. Furthermore, they were concerned about the detrimental effects on the doctor-patient relationship of providing lifestyle advice to all patients. GPs believed that a multi-agency, centrally co-ordinated approach was the preferred way to improve population health and that their role should be limited to secondary prevention. CONCLUSION: Large amounts of resources would be necessary to convince GPs to adopt a population approach to lifestyle advice. Measures to tackle the social and environmental determinants of health may be a more effective and efficient means of improving the nation's health.