The foundation run by Microsoft magnate Bill Gates has announced it is dedicating $750m (£400m) to a worldwide infant vaccination programme.
Mr Gates has used his wealth in the battle against disease
Mr Gates said the donation would help save millions of children's lives.
"Supporting children's immunisation is undoubtedly the best investment we've ever made," he said in a statement.
At the same time, it was announced that Norway was donating $290m to the same organisation, the Global Alliance for Vaccination and Immunisation (Gavi).
Mr Gates' pledge is to run over 10 years, and Norway's over five.
Mr Gates has made a name as one of the world's top philanthropists. The Bill and Melinda Gates Foundation has pledged $7bn to good causes over the last decade.
The Microsoft founder is expected to press the case for further investment in disease prevention at this week's annual World Economic Forum meeting in Davos, Switzerland.
He is due to share a platform with Britain's Prime Minister Tony Blair for a debate on healthcare funding.
On Tuesday he appealed to other donors to help fund Gavi's goal - to immunise all the world's children.
Gavi was set up in 2000 to co-ordinate worldwide vaccination programmes, and has already immunised 54 million children against diseases such as diphtheria, tetanus, whooping cough, hepatitis B, influenza type B, and yellow fever.
"In just five years, Gavi's efforts have saved hundreds of thousands of children's lives, and its work in the coming years will save millions more," said Mr Gates.
"Gavi will use the funds announced today to support national immunisation programmes in 72 of the world's poorest countries."
The commitment was welcomed by Gavi chairman Dr Jong-wook Lee, who said it would "prevent immense suffering and disability over the coming years".
The Gates Foundation said current vaccination efforts were failing to reach an estimated 27 million children in developing countries every year, leading to millions of deaths.