A statement from the band said that singer Alan Donohoe is suffering from exhaustion and a throat infection.
At the Reading and Leeds festival in the UK last weekend, the band played without Donohoe, and managed to muster up a few random replacements in the form of members of the Bloc Party, Maximo Park and Towers Of London.
They're the second band to cancel playing the festival. The Subways have also had to retract their appearance due to unspecified commitments in the UK.