The realisation of the right to health for millions of people in poor countries depends upon a massive increase in health services to achieve universal and equitable access. A growing number of international donors are promoting an expansion of private-sector health-care delivery to fulfil this goal. The private sector can play a role in health care. But this paper shows there is an urgent need to reassess the arguments used in favour of scaling-up private-sector provision in poor countries. The evidence shows that prioritising this approach is extremely unlikely to deliver health for poor people. Governments and rich country donors must strengthen state capacities to regulate and focus on the rapid expansion of free publicly provided health care, a proven way to save millions of lives worldwide.