This paper attempts to pull together and review key pieces of evidence about the cost effectiveness of prevention. The findings, which reflect a paucity of quantified information about the effectiveness of preventive interventions, suggest that there is a strong financial case for reducing hospitalisation (particularly through falls) and for reducing the rate of institutionalisation by maintaining independence. Small-scale trials show that small interventions could prevent falls and reduce the rate of institutionalisation. However, establishing a direct causal relationship between such interventions and long-term financial savings has proved problematic although. There is a lack of consensus over the cost effectiveness of intermediate care although there is evidence that it is cost effective when targeting specific groups/illnesses/events such as stroke and falls. Evidence for secondary stroke prevention services is perhaps the strongest, and most widely quantified, body of research. There is some evidence that primary prevention strategies (such as smoking cessation and reduced salt intake) have potential to reduce the incidence of stroke. The paper makes a series of recommendations, calling for a greater focus on low-level interventions, particularly where there is qualitative evidence that they are valued by service users; implementation of promising interventions, even if not supported by robust evidence, accompanying by formal evaluation during roll-out; development of standard outcome measures of prevention; targeting resources to ensure greatest impact; and greater integration between health and social care services as a drive to shift services towards the preventive end of the spectrum.