Robin Williams has postponed the rest of his comedy tour to have heart surgery.

A statement just released by his reps says Robin will have "to undergo surgery for an aortic valve replacement" -- and said his tour will hopefully pick back up in the fall.

The release also included this statement from Williams:

"I'm so 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."