The crisis of human resources for health that is affecting low-income countries and especially sub-Saharan Africa has been attributed, at least in part, to increasing rates of migration of qualified health staff to high-income countries. We describe the conditions in four Organisation for Economic Cooperation and Development (OECD) health labour markets that have led to increasing rates of immigration. Popular explanations of these trends include ageing populations, growing incomes, and feminisation of the health workforce. Although these explanations form part of the larger picture, analysis of the forces operating in the four countries suggests that specific policy measures largely unrelated to these factors have driven growing demand for health staff. On this basis we argue that specific policy measures are equally capable of reversing these trends and avoiding the exploitation of low-income countries' scarce resources. These policies should seek to ensure local stability in health labour markets so that shortages of staff are not solved via the international brain drain.