Yahoo chief executive Scott Thompson has resigned amid accusations his CV featured a computer science degree that he never received.
The announcement was made at an emergency board meeting, just over a week after the allegations surfaced.
A statement from Yahoo said only that Mr Thompson had "left the company".
He was said to have studied for a computer science degree at Stonehill College, a Catholic school near Boston, in 1979.
But while he gained an accounting degree from the college, it has been claimed he could not have earned a computer science degree as the course was not offered at the time.
The information was revealed by hedge fund manager Daniel Loeb, who is credited with bringing about the resignation of the company's co-founder Jerry Yang in January, and its former chairman Roy Bostock.
A separate report in the Wall Street Journal said Mr Thompson had told colleagues over the weekend he had been diagnosed with thyroid cancer before resigning.
Yahoo has appointed its head of global media Ross Levinsohn as interim chief executive and Fred Amoroso as chairman of the board, with immediate effect.
Mr Levinsohn will be the company's third chief executive in three years.
The firm had hired Mr Thompson, the former head of eBay's PayPal, in January to help turn around its fortunes after Carol Bartz was sacked just nine months into her tenure.
Even though Yahoo is one of the internet's most-visited websites, it has struggled to grow in the face of stiff competition from the likes of Google and Facebook.