Facebook's founder Mark Zuckerberg and his wife Priscilla Chan have pledged $3bn (£2.3bn) to fund medical research over the next decade.
At a press conference in San Francisco, they said their ultimate goal was to "cure, prevent or manage all diseases by the end of the century".
The funds will be distributed by the Chan Zuckerberg Initiative, which they created in December 2015.
Tech leaders are increasingly turning their attention to health.
Earlier in the week, Microsoft said it intended to "solve" cancer by using artificial intelligence tools.
Google's DeepMind unit is working with the NHS to find a way to use computers to more accurately diagnose diseases.
And IBM and MIT announced a tie-up earlier this week to develop AI-based systems that could help clinicians improve the care of elderly and disabled patients.
Even so, the Chan Zuckerberg plan is marked by its ambition.
Analysis by James Gallagher, health and science reporter, BBC News
This is certainly an ambitious project, but is $3bn (£2.3bn) over the next decade enough to fulfil it?
One British charity - Cancer Research UK - is likely to spend more in that time on just one disease. Its research budget is currently $0.5bn (£404m) a year.
The Wellcome Trust - the world's biggest medical research charity - is investing significantly more: $6.5bn (£5bn) over the next five years.
And the US' medical research agency, the National Institutes of Health, spends a whopping $32.3bn (£25bn) every year.
There is no doubt that the Chan Zuckerberg Initiative could make a real impact - the Bill and Melinda Gates Foundation has given real impetus to eliminating malaria.
And advances in technology are transforming and accelerating medical research - for example, cancer drugs designed by artificial intelligence are showing success in clinical trials.
But curing, preventing or managing all disease remains a lofty and distant goal.
Mr Zuckerberg said that at present 50 times more money was spent on treating people who are sick than on curing the diseases that would stop them getting ill in the first place, and added that this needed to change.