Saddam Hussein, Harry Potter and the deaths of Michael Jackson and Australian conservationist Steve Irwin were also hot topics, according to the list released by the company to mark its 15th birthday.
The figures also reveal that the number of websites has reached an estimated 200 million from just 18,000 in 1995, with the number of users increasing from 10 million globally, or less than 0.33 per cent of the world's population, 15 years ago to the current 1.6 billion or 25 per cent, Yahoo! said.
Yahoo! co-founders Jerry Yang and David Filo said: ''These numbers are astonishing, but even more important and more exciting is the impact that the internet is having on so many people around the world.
''From socio-economic opportunities to more accessible healthcare to educating the next generation and beyond, the internet has changed the way we live, work and learn.''
The top 10 news searches in the last 15 years according to Yahoo! are:
1. September 11
3. Iraq war
4. Saddam Hussein
5. Harry Potter book releases
6. Michael Jackson death
7. Steve Irwin death
9. Enron scandal
10. The Millennium http://www.telegraph.co.uk/technology/news/7377257/September-11-attacks-and-cloning-top-Yahoo-searches.html