Aerosmith singer Steve Tyler underwent foot surgery last year
Aerosmith bassist Tom Hamilton has been forced to pull out of part of the band's summer tour as he recovers from surgery, according to their website.
A statement said David Hull, who played in the Joe Perry Project, will replace Hamilton as he "recuperates from non-invasive surgery".
Earlier this summer, the band postponed seven shows after Steve Tyler, 61, injured his leg at a gig in June.
Guitarist Brad Whitford also missed some dates after hurting his head.
However, Whitford returned to the stage on Wednesday night at the Lakewood Amphitheatre in Atlanta.
It is not the first time medical problems have plagued the band.
In January this year, the band cancelled a gig in Venezuela after guitarist Joe Perry developed "unforeseen complications" with his replacement knee.
And in 2006, the band were forced to cancel several US tour dates while Tyler had throat surgery.
He also checked into rehab last year to recuperate from foot surgery.
The band are expected to wrap up their Guitar Hero tour with ZZ Top in September in Detroit, but are in the process of rescheduling the dates which were postponed while Tyler was injured.
Aerosmith had their first US number one in 1998 with ballad I Don't Want To Miss A Thing.
Other hits include Cryin', Dude (Looks Like A Lady) and Walk This Way.