Martyn Williams' sin-binning cost the home side dear
Blues: (6) 12
Pens: Blair (4)
Munster: (13) 22
Pens: O'Gara (5)
Munster took control of Pool Four and all but ended Cardiff Blues' Heineken Cup hopes with a hard-fought win.
The home side started well with two Ben Blair penalties, but a Martyn Williams sin-binning cost them dear as Denis Leamy ploughed over for Munster 's try.
Ronan O'Gara's boot took his side 13-6 clear at the break, but Blair closed the gap to a point with two penalties.
The visitors showed their experience to turn the screw though as three more O'Gara penalties completed the win.
The victory broke Leicester's Heineken Cup record of five successive away victories.
They will be looking to break the Tigers' mark of 11 successive wins in next Saturday's return with the Blues at Thomond Park.
The home side opened dynamically in front of a packed house at a rain-drenched Cardiff Arms Park.
Blair missed a first-minute penalty, but was on target three minutes later after Irish hands went into a ruck.
A sniping Mike Phillips break helped win another penalty - converted by Blair - as Munster prop Frederico Pucciariello was sin-binned for kneeing Scott Morgan at a ruck.
The home side failed to take advantage of the extra man, though, turning over ball and giving O'Gara his first penalty.
As Pucciariello came back onto the field, Blues flanker Williams was harshly sin-binned for an accidental high tackle.
O'Gara kicked 17 points for the visitors
A fine Blair tackle denied Pucciariello a try from a blind-side snipe, but O'Gara kept the home side pinned near their own line.
The European champions' trademark, patient rolling maul then took control, giving an armchair ride for Leamy to drop over for the simplest of tries, converted by O'Gara.
With half-time beckoning, Blues flanker Morgan conceded a foolish penalty, and O'Gara made no mistake from long range to take the lead to 13-6 at the break.
The Blues powered into the second half, carrying strongly and forcing penalties from the under-pressure visitors.
After one wasted penalty kick to the corner, Blair was given the two shots at goal that cut the deficit to a point.
But Munster turned on the pressure at the set piece, and turnover ball from a scrum gave O'Gara his third successful penalty.
The visitors showed their experience to baton down the hatches, and were rewarded as O'Gara stretched the lead to seven points after a Morgan high tackle on David Wallace.
O'Callaghan showed flashes of his talent at the Arms Park
Events took a surreal twist with Munster lock Donnacha O'Callaghan insisting he could play on in his bright red underpants rather than waiting for a replacement pair of shorts.
And his commitment to the cause was rewarded when James Goode pulled him down at the following line-out, giving O'Gara the penalty that secured the game and cost the Blues a losing bonus point.
In the closing minutes, Blues coach Dai Young hauled off Nicky Robinson, the former's body language suggesting he was unimpressed with his outside-half's control of the game.
Blues coach Dai Young:
"It was typical Munster. You don't win the Heineken Cup by accident, and they ground out the win.
"We had equal amounts of pressure and territory, but we failed to come away with points at crucial times, whereas they scored a try when we had a player sin-binned.
"We have a huge respect for Munster and we know it will be a hugely formidable task for us next week.
"Losing this game has made our life very difficult, but we will go out with all guns blazing next Saturday. We are not giving up, that is for sure."
Munster coach Declan Kidney:
"This was a great win for us and it was a really tough game, and next week is a long, long way from being a foregone conclusion.
"We are at just the halfway stage of the group, and it could be a case of having to win all six games to come through the pool."
Blues: Blair; Shanklin, J. Robinson, Stcherbina, Czekaj; N Robinson, Phillips; Jenkins, Thomas, Filise; Jones, Goode; Morgan, M Williams, Rush.
Replacements: Macleod for N. Robinson (77), Yapp for Jenkins (41), Davies for Goode (61), Lewis for Morgan (76). Not Used: Goodfield, Fairhurst, James.
Sin Bin: M Williams (22).
Munster: Payne; O'Leary, Mafi, Halstead, Dowling; O'Gara, Stringer; Pucciariello, Sheahan, Hayes; O'Callaghan, O'Connell; Quinlan, Wallace, Leamy.
Replacements: D. Hurley for Pucciariello (59). Not Used: Kyriacou, Wyatt, O'Sullivan, Mateus, Manning, Cullen.
Sin Bin: Pucciariello (10).
Referee: Christophe Berdos (France).