US companies increased charitable donations by 14% in 2005, though giving as a proportion of profits and revenues fell slightly, according to a survey.
Bill Gates is one of the world's richest men and top philanthropists
The Committee to Encourage Corporate Philanthropy said that the 91 companies it surveyed gave $10bn last year.
This was thought to be about half of all US corporate giving, with Wal-Mart and Citigroup among the largest donors.
But while giving climbed 14%, average income among 62 of the donors studied was up 17%, while profits rose 15%.
More than $300m of the $10bn was given for relief after hurricanes on the Gulf Coast.
Charities linked to the Asian Tsunami were also recipients.
The annual study found that employers were putting more emphasis on involvement with charities, with most having at least one volunteer programme.
Almost half offered paid time-off for staff to get involved in charitable projects .
Others gave awards recognising volunteering and matched money raised by staff.
As well as being one of the world's richest men, Microsoft's billionaire co-founder Bill Gates is one of the world's top philanthropists.
In the last decade a foundation set up with his wife Melinda has given more than $10bn to good causes.
Recent projects include donating $750m to a worldwide infant vaccination scheme.