Background: WHO recommends routine use of rotavirus vaccines in all countries, particularly in those with high mortality attributable to diarrhoeal diseases. To establish the burden of life-threatening rotavirus disease before the introduction of a rotavirus vaccine, we aimed to update the estimated number of deaths worldwide in children younger than 5 years due to diarrhoea attributable to rotavirus infection. Methods: We used PubMed to identify studies of at least 100 children younger than 5 years who had been admitted to hospital with diarrhoea. Additionally, we required the studies to have a data collection midpoint of the year 2000 or later, to be done in full-year increments, and to assesses diarrhoea attributable to rotavirus with EIAs or polyacrylamide gel electrophoresis. We also included data from countries that participated in the WHO-coordinated Global Rotavirus Surveillance Network (consisting of participating member states during 2009) and that met study criteria. For countries that have introduced a rotavirus vaccine into their national immunisation programmes, we excluded data subsequent to the introduction. We classified studies into one of five groups on the basis of region and the level of child mortality in the country in which the study was done. For each group, to obtain estimates of rotavirus-associated mortality, we multiplied the random-effect mean rotavirus detection rate by the 2008 diarrhoea-related mortality figures for countries in that group. We derived the worldwide mortality estimate by summing our regional estimates. Findings: Worldwide in 2008, diarrhoea attributable to rotavirus infection resulted in 453 000 deaths (95% CI 420 000-494 000) in children younger than 5 years-37% of deaths attributable to diarrhoea and 5% of all deaths in children younger than 5 years. Five countries accounted for more than half of all deaths attributable to rotavirus infection: Democratic Republic of the Congo, Ethiopia, India, Nigeria, and Pakistan; India alone accounted for 22% of deaths (98 621 deaths). Interpretation: Introduction of effective and available rotavirus vaccines could substantially affect worldwide deaths attributable to diarrhoea. Our new estimates can be used to advocate for rotavirus vaccine introduction and to monitor the effect of vaccination on mortality once introduced. Funding: None.