Sir Elton John was hospitalised in Los Angeles on Wednesday (23May12) after falling ill with a serious respiratory infection.
The Rocket Man checked into Cedars-Sinai Medical Center in the early hours and was subjected to a series of tests.
Sir Elton was told he needed "complete rest and antibiotic treatment to prevent damage" and doctors ordered him to take seven days off from performing.
As a result, he's scrapped this week's (ends27May12) upcoming shows in Las Vegas.
The star tells Tmz.com, "It feels strange not to be able to perform these Million Dollar Piano concerts at the Colosseum... I love performing the show and I will be thrilled when we return to the Colosseum in October to complete the 11 concerts.
"All I can say to the fans is, 'Sorry I can't be with you.'"
The website reports Sir Elton has since been released from the hospital.