Large parts of the world have not enjoyed the remarkable global progress in health conditions that have taken place over the past century. Indeed, millions of deaths in impoverished nations are avoidable with prevention and treatment options that the rich world already uses. This year, 10 million children will die in low- and middle-income countries. If child death rates were the same as those in developed countries, this figure would be lower than one million. Conversely, if child death rates were those of rich countries just 100 years ago, the figure would be 30 million. The key difference between now and then is not income but technical knowledge about the causes of disease, and interventions to prevent disease, or at least the most pernicious symptoms. Today's tools for improving health are so powerful and inexpensive that health conditions could be improved even in poor countries. Recent research for the Copenhagen Consensus identifies six highly cost-effective options that would tackle some of the planet's most urgent health problems. The most promising investment is in tuberculosis (TB) treatment. Some 90 per cent of the 1.6 million TB deaths in 2003 occurred in low- and middle-income countries. Because TB affects working-age people, it can be a trigger for household poverty. The cornerstone of control is prompt treatment using first-line drugs, which doesn't require a sophisticated health system. Spending $1 billion on TB treatment in a year would save one million lives. The second most cost-effective investment is tackling cardiovascular disease. Heart disease might not seem like a pressing issue for poor nations, but it represents more than a quarter of their death toll. Measures to reduce risk factors other than smoking