Rotavirus is the leading cause of severe childhood diarrhea worldwide. Studies from 1986 to 1999 showed it caused about 22% of childhood diarrhea hospitalizations, increasing to 39% from 2000 to 2004. Applying this proportion to WHO estimates, rotavirus caused approximately 611,000 deaths annually. Earlier estimates suggested 873,000 annual deaths, but this has decreased as global diarrhea deaths have declined. Recent studies indicate that as global childhood diarrhea deaths have decreased, the proportion of rotavirus-related hospitalizations has increased. For example, in 9 Asian countries, 45% of children hospitalized with diarrhea tested positive for rotavirus, higher than previous studies. In Vietnam, 56% of children hospitalized with diarrhea tested positive for rotavirus, compared to 21% in earlier studies. A review of studies from 2000 to 2004 found that the median detection rate of rotavirus in children hospitalized with diarrhea was 39%, with higher rates in low- and middle-income countries. This rate was higher than in previous studies, suggesting a possible increase in rotavirus's role in severe childhood diarrhea. The study found that rotavirus causes approximately 611,000 childhood deaths annually, with over 80% occurring in low-income countries in south Asia and sub-Saharan Africa. The increase in rotavirus detection may be due to slower decreases in rotavirus hospitalizations compared to other causes of severe diarrhea, and the difficulty of treating severe vomiting in children. The study highlights the need for updated data on rotavirus hospitalizations and diarrhea deaths to refine estimates. New data from countries like India and China, which account for a large fraction of global rotavirus deaths, will help improve these estimates. Policymakers need this information to assess the impact of rotavirus and the value of new vaccines.Rotavirus is the leading cause of severe childhood diarrhea worldwide. Studies from 1986 to 1999 showed it caused about 22% of childhood diarrhea hospitalizations, increasing to 39% from 2000 to 2004. Applying this proportion to WHO estimates, rotavirus caused approximately 611,000 deaths annually. Earlier estimates suggested 873,000 annual deaths, but this has decreased as global diarrhea deaths have declined. Recent studies indicate that as global childhood diarrhea deaths have decreased, the proportion of rotavirus-related hospitalizations has increased. For example, in 9 Asian countries, 45% of children hospitalized with diarrhea tested positive for rotavirus, higher than previous studies. In Vietnam, 56% of children hospitalized with diarrhea tested positive for rotavirus, compared to 21% in earlier studies. A review of studies from 2000 to 2004 found that the median detection rate of rotavirus in children hospitalized with diarrhea was 39%, with higher rates in low- and middle-income countries. This rate was higher than in previous studies, suggesting a possible increase in rotavirus's role in severe childhood diarrhea. The study found that rotavirus causes approximately 611,000 childhood deaths annually, with over 80% occurring in low-income countries in south Asia and sub-Saharan Africa. The increase in rotavirus detection may be due to slower decreases in rotavirus hospitalizations compared to other causes of severe diarrhea, and the difficulty of treating severe vomiting in children. The study highlights the need for updated data on rotavirus hospitalizations and diarrhea deaths to refine estimates. New data from countries like India and China, which account for a large fraction of global rotavirus deaths, will help improve these estimates. Policymakers need this information to assess the impact of rotavirus and the value of new vaccines.