Trimble is part of an unchanged backline from the one that helped Ulster to secure a 3-10 away success over Connacht last weekend, their fourth successive win.
Louis Ludik and Rory Scholes continue in the back three for this important Guinness PRO12 clash, with Stuart McCloskey and Luke Marshall named in midfield and Paddy Jackson and Ruan Pienaar included in the half back positions.
Rory Best will return to captain the side from hooker, in one of four changes up front. Director of Rugby, Les Kiss, has also recalled loosehead prop Kyle McCall to the front row alongside Wiehahn Herbst, who remains at tighthead.
Lewis Stevenson has earned a start in the second row, where he is partnered by Franco van der Merwe.
Chris Henry has overcome a slight shoulder injury and is selected at openside flanker, with Robbie Diack and Nick Williams retaining their places in the other back row spots.
Rob Herring, Callum Black, Ricky Lutton, Alan O'Connor and Roger Wilson are back up for the forwards, while Paul Marshall, Ian Humphreys and Sammy Arnold again provide backline cover.
The match will be televised live on Sky Sports.
Ulster team & replacements to face Munster, Guinness PRO12, Kingspan Stadium, Saturday 2nd January 2016 (kick off 3.00pm):
(15-9): L Ludik, A Trimble, L Marshall, S McCloskey, R Scholes, P Jackson, R Pienaar;
(1-8): K McCall, R Best (captain), W Herbst, L Stevenson, F van der Merwe, R Diack, C Henry, N Williams;
Replacements (16-23): R Herring, C Black, R Lutton, A O'Connor, R Wilson, P Marshall, I Humphreys, S Arnold.
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