"Give it away, you'll enjoy it," Gates tells rich

OSLO (Reuters Life!) - Microsoft founder Bill Gates said on Wednesday that billionaires ought to give away most of their wealth to charitable causes, and they would even find they enjoyed it.

Gates has given much of his wealth from Microsoft, the U.S. software giant that made him the world's richest man, to the Bill & Melinda Gates Foundation, a philanthropic powerhouse.

"I think all billionaires should give away the vast majority of their fortunes -- though I don't say they shouldn't leave anything to their kids," Gates told a gathering at Oslo's opera house.

"I think they would enjoy it, their kids would be better off, and the world would be better off," Gates said.

"I'm a great believer that great wealth should go from the richest to the poorest," he said, seated next to his wife Melinda who co-chairs the foundation.

Gates renewed his appeal to eradicate polio, saying the goal was well within reach, which would make it the second major communicable disease entirely wiped out after smallpox in the late 1970s.

"We have to get rid of polio because if we don't, it will spread back and we will have millions affected," he said.

Gates said his foundation's biggest success had been in the field of vaccination.

"Vaccination is the area where we have saved millions of lives, and there is more to be done."