He was supposed to perform this Thursday, Friday and Saturday.
Manilow has been undergoing intense physical therapy after hip surgery. His doctors say he is not strong enough to get back onstage.
Quoting Barry, "My hips just aren't ready yet, and these hips don't lie."
Tickets will be honored at concerts this summer on July 12 for February 2, July 13 for February 3, and July 14 for February 4 seats.