Methods This study used the same methods as originally presented by the Bellagio group in Lancet, 2003, vol.362, pp For each country and for each life-saving intervention, we estimated the increase in coverage necessary to achieve universal coverage and combined this with estimates of intervention efficacy to estimate the potential number of deaths that could be thus prevented. These deaths averted were removed from the total current number of deaths, and the exercise was repeated for an additional intervention, until all interventions of demonstrated efficacy were exhausted. The model differs from that presented in 2003 in the following major respects: The current coverage of efficacious interventions was updated to reflect the situation in 2003, as reported in State of the World’s Children Population estimates were updated to reflect the situation in 2003, as reported by the UN Population Division. The ‘baseline’ proportional distribution of child deaths by cause in country was that estimated by WHO and reported (at an aggregate level) in the World Health Report Interventions for the neonatal period were taken from Lancet 2005, Vol.365, pp , using the mid-point efficacy. The list of countries was modified to include those currently having under-five mortality rates greater than or equal to 90 per 1000 live births or total number of under-five deaths greater than or equal to 50,000 (the 60 UNICEF priority countries). Universal coverage was defined as 99% for all interventions, with no exceptions. Background The 2003 Lancet Child Survival Series estimated, for the year 2000, the distribution of under-five deaths by cause and the proportion that could be prevented by making universally available all child survival interventions of demonstrated efficacy. New information has since become available on under-five mortality rates, world population, the coverage of life-saving interventions, and the epidemiology of neonatal deaths (Lancet 2005, Vol.365, pp ). The estimates published in 2003 may therefore no longer reflect current circumstances. This study aims to update cause-specific estimates of under-five deaths and the proportion of deaths preventable using existing interventions, using 2003 as the new reference year. How many child deaths can we prevent? Best estimates for Saul S Morris, Robert E Black, Kenji Shibuya, Simon N Cousens, Jennifer Bryce, Gary L. Darmstadt Results Of the 10.6 million under-five deaths in 2003, 9.9 million (93%) took place in one of the 60 priority countries. 6.3 million deaths (63%) could have been averted by scaling up 26 efficacious interventions so that they reached all those in need. Table 1 shows deaths averted by cause. The Figures show the proportion of deaths that could be averted by scaling up each intervention in turn, leaving the coverage rates of all other interventions unchanged. Abstract In 2003, the Bellagio study group estimated the numbers of under-five deaths that could be prevented by making efficacious child survival interventions universally available. Subsequent changes in world population, mortality rates, and intervention coverage, as well as the publication of a new series of estimates of the by-cause distribution of deaths in each country and a recent review of interventions for the neonatal period, make it appropriate to update these estimates. Out of a total of 9.9 million deaths taking place in 60 high risk countries in 2003, 63% could have been averted using currently available technology. The interventions that have the greatest life-saving potential if implemented in isolation are much as previously identified. Conclusions and Recommendations Approximately two-thirds of child deaths can be averted with existing interventions. In the future, this model needs updating to include a range of interventions for which new efficacy data are now available. These include: pneumococcal and rotavirus vaccines, handwashing, chlorhexidine cleansing of the cord, and others.