Paul O'Connell will captain the side when they run out in Murrayfield at 1.35pm on Saturday.
With O'Mahony ruled out there is one change to the pack that defeated Leinster last weekend with Paddy Butler coming into the squad and making his first Heineken Cup start this Saturday, as he joins Niall Ronan and James Coughlan in the back-row.
There is one change to the back-line also with Conor Murray moving into the starting XV with Duncan Williams named in the replacements.
Munster: Felix Jones; Keith Earls, Casey Laulala, James Downey, Simon Zebo; Ian Keatley, Conor Murray; Dave Kilcoyne, Mike Sherry, Stephen Archer; Donncha Ryan, Paul O'Connell Capt.; Paddy Butler, Niall Ronan, James Coughlan. Replacements: Damien Varley, James Cronin, BJ Botha, Donncha O'Callaghan, CJ Stander, Duncan Williams, JJ Hanrahan, Denis Hurley.