Williams said he was touched by all the good wishes from fans
Comedian Robin Williams is to have heart surgery and has postponed the remaining shows of his one-man stand-up tour, a spokeswoman has said.
Williams, 57, had already called off four shows in Florida earlier this week after experiencing shortness of breath.
He will undergo surgery for an aortic valve replacement and hopes to restart the tour in the autumn.
In a statement on his website, Williams said he had been "touched by everyone's support and well wishes".
"This tour has been amazing fun and I can't wait to get back out on the road after a little tune-up," he said.
William's has been on tour with his 80-date sell-out Weapons of Self-Destruction show since September last year.
The veteran comedian is best known for his role in classic TV sitcom Mork and Mindy and for his Oscar-winning performance in Good Will Hunting.
He will be seen in cinemas later this year reprising his role as President Teddy Roosevelt in Battle of the Smithsonian, the sequel to Night at the Museum.