Microsoft pioneer Bill Gates has dunked himself in ice water for the Ice Bucket Challenge.
The multi-billionaire was nominated by Facebook's Mark Zuckerberg, to take on the challenge to raise awareness for ALS, also known as Lou Gherig's disease, or motor neurone disease.
The challenge involves nominating people to tip ice water over themselves to raise awareness of ALS.
If a nominee does not take up the challenge within a day they must make a donation to the cause.
Gates posted a slow motion video of the entire challenge on his gatesnotes blog. The video shows Zuckerberg nominating him and then rigging up an elaborate tipping mechanism, before the Facebook boss's dunking.
The 58-year-old appears to weld the structure before pulling the cord and releasing the icy water over his head.
The Microsoft co-founder nominated other famous entrepreneurs to take a dip in the 90-second clip, saying: "I'm going to challenge three more people - Elon Musk (of SpaceX and Tesla electric cars); Ryan Seacrest (American Idol host); and Chris Sanderson (curator of the TED conferences). You have 24 hours - good luck!"
Charities have reported an increase in donations after the campaign went viral, with celebrities such as Justin Timberlake and US talk show host Jimmy Fallon also taking on the icy challenge for charity.
Gates, who is worth an estimated $80.2bn (£48bn), is renowned for his philanthropy through the charitable foundation he runs with his wife.
In the UK, Macmillan Cancer Support is also using the Ice Bucket Challenge to raise awareness and donations.