Mark Zuckerberg and Priscilla Chan have vowed to spend US$3 billion over the next decade to try and cure all diseases.
The Facebook founder and his wife, who pledged to give away 99 per cent of their wealth to good causes following the birth of their daughter last year, said the money would be used to assist scientific work and build new research tools.
The goal, which they are unlikely to live to see accomplished, is to "cure, prevent or manage all disease" in the next 80 or so years.
"So if you even just assume that we'll be able to continue to make progress on that same trajectory, then that implies that by the end of this century we will have been able to solve most of these types of things," Zuckerberg said in an interview with Associated Press.
He and Chan, who has worked as a paediatrician, have spent the past two years speaking to scientists and other experts to plan the endeavour.
He emphasised "that this isn't something where we just read a book and decided we're going to do.
"We spend 50 times more on health care treating people who are sick than we spend on science research (to cure) diseases so that people don't get sick in the first place," Zuckerberg said.
He added that the approach reflects a belief that "people are always going to suffer from disease so therefore we should focus on treating people who are sick."
The Facebook founder is worth about US$56b, thanks to shares in his own company. Zuckerberg has asked other shareholders to allow him to give away his stock without losing control of the company.
Their announcement comes a day after Microsoft made a pledge to "solve the problem of cancer" within a decade by reprogramming diseased cells.