President George W Bush has said the US will help provide 5.2 million mosquito nets as part of a broader campaign to tackle malaria in sub-Saharan Africa.
Mr Bush handed out bed nets on his visit to Arusha
Mr Bush announced the plan during a visit to a hospital in Arusha, Tanzania, where he is on the second leg of a tour of five African countries.
He said it would provide free nets for every Tanzanian child aged one to five.
Malaria is the main cause of death for children in Africa, killing a child every 30 seconds, the UN says.
The US, Tanzania and the Global Fund to fight Aids, Tuberculosis and Malaria will distribute the nets.
"This is one of the simplest technologies imaginable, but it's also one of the most effective," Mr Bush said after visiting the Meru District Hospital.
"It is unacceptable to people here in Africa, who see their families devastated and their economies crippled," he said.
"It is unacceptable to people in the United States who believe every human life has value, and that the power to save lives comes with the moral obligation to use it."
In 2005 President Bush launched a $1.2bn (£610m) five-year campaign to lower malaria deaths in Africa.
One in every five childhood deaths in Africa is due to the effects of the disease, according to the World Health Organization.