Effective public health interventions can save hundreds of millions of lives in developing countries, as well as create broad social and economic benefits. Unfortunately, public health approaches and solutions applied in developed countries are often assumed to be inappropriate or unattainable in developing countries. This has sometimes forestalled effective interventions in parts of the world where they are most needed, despite conditions that now facilitate lasting solutions to both long-standing and emerging global public health problems. Core public health functions are similar regardless of a country's income level. Although some resource-intensive approaches from industrialised nations are inappropriate in less developed countries, many basic public health measures achieved decades ago in developed countries are urgently needed, highly appropriate, extremely cost-effective and eminently attainable in developing countries today. About half of the disease burden in low and middle-income countries is now from non-communicable diseases, but non-communicable disease epidemics that will otherwise increase rapidly in the developing world can be avoided or reversed. Progress of public health in developing countries is possible, but will require sufficient funding and human resources; improved physical plant and information systems; effective programme implementation and regulatory capacity; and, most importantly, political will at the highest levels of government.