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.