The billionaire founder of the computer giant Microsoft donated the cash from his personal charity to fund a state-of-the-art new home for the university's computer department.
However, despite its generosity, his gift places him lower down the philanthropists' league table than CNN founder Ted Turner, who made history a fortnight ago with a $1bn (pounds 580m) personal donation to the United Nations. Mr Turner's money, to be paid in $100m installments over ten years, will finance programmes for refugees, children and clearing landmines.
Mr Gates' gift, paid through his charity, the William H Gates Foundation, to the Cambridge University Development Office in America, comes only five months after Microsoft announced plans to develop a multimillion- pound new research campus intended to help turn Cambridge into a technological powerhouse to rival America's Silicon Valley.
The billionaire said yesterday: "Cambridge is one of the great research universities in the world. Its facilites and excellence in computer science demonstrate a unique ability to build on a legendary tradition of learning while also focusing steadily on the future."
The Turner donation, the largest by any single benefactor in history, sparked predictions in America of philanthropic one-upmanship as billionaires competed to give their wealth away. Mr Turner openly challenged others with large fortunes to follow "I am putting every rich person in the world on notice," he told the CNN interviewer Larry King. "There's a lot of people who are awash in money they don't know what to do with".