The veteran rockers postponed a show in Concord, California last night (13.08.14) ''due to illness'' and it has now been claimed by gossip website TMZ that the 64-year-old musician - who has had heart problems in the past - is to undergo surgery for the unspecified complaint.
The Concord Pavilion announced the group were cancelling the show just hours before doors at the venue were due to open.
They wrote on their Facebook page: ''Due to illness, Aerosmith has been forced to cancel tonight's performance at the Concord Pavilion in Concord, CA.
''The band regrets not being able to perform for their fans. Refunds will be available at point of purchase.''
A spokesperson for the band didn't go into specific details about the late cancellation, saying only that they ''apologise for the inconvenience''.
It is as yet unclear whether the 'Crazy' hitmakers will complete their current US tour, but according to TMZ, members of the crew have already been told the next gig, in Washington on Saturday (16.08.14), won't be going ahead.