A new study says malnutrition is the root cause of some 2.6 million child deaths each year.
The report from an international aid group, Save the Children, says that despite global efforts to end hunger, malnutrition remains a largely ignored problem that affects a quarter of the world's children.
The study, conducted in December and January, says that 300 children die every hour because of malnutrition.
The group says rising food prices have forced children in many countries to quit school to help their families earn money.
In many cases, the report said, malnutrition was not only the result of not having enough to eat, but because families cannot afford nutritious food.
Save the Children is urging British Prime Minister David Cameron to hold a world hunger summit on the sidelines of the 2012 Olympic games to be held in London later this year.
It said 90 percent of the world's most vulnerable children could be protected from malnutrition for as little as $10 billion a year.
Some information for this report was provided by AP and Reuters.