Dragons (6) 9
Pens: Arlidge 3.
Munster (13) 20
Tries: O'Boyle, Horgan. Cons: Warwick 2. Pens: Warwick 2.
Ciaran O'Boyle scores Munster's opening try against the Dragons
Munster retook top spot in the Magners League with victory away to a dogged Newport Gwent Dragons side.
Ciaran O'Boyle's try from a well-worked backs move gave Munster the edge at half-time as they led 13-6.
A third penalty from Dragons fly-half James Arlidge brought the Welsh side back to within striking distance and Munster were forced to defend fiercely.
But Munster worked an overlap on the wing for Anthony Horgan to squeeze over at the left corner flag.
With the rain hammering down at Rodney Parade, the game was never likely to produce a spectacle of running rugby.
What the crowd did get within 30 seconds was a mass brawl between the two sets of forwards that set the tone for a niggly game.
Referee Allan Lewis restored calm after that early spat and Munster were soon rolling their way through the phases and into Dragons territory.
The Welsh gave up a penalty in their attempts to slow down Munster possession and Paul Warwick stroked the regulation kick between the posts.
Arlidge replied for the Dragons with his own kick, but Munster retook the lead when Denis Hurley timed his run from full-back to perfection to send O'Boyle over.
Warwick converted and added a second penalty soon after to stretch Munster's lead, only for Arlidge to kick the Dragons back to 6-13.
Munster's half-time advantage should have been more, though, as they failed to take advantage when Dragons flanker Richard Parks had been sin-binned for another offence at the breakdown.
Warwick's penalty miss from that offence was understandable as he took on a kick from the halfway line, but the fly-half was then wide with a straight-forward kick in injury time.
Munster lost their own man to the sin-bin soon after the restart as prop Darragh Hurley was punished for a clumsy challenge, but Arlidge failed with the resulting penalty.
It seemed certain that the Dragons would claim a try when prop Rhys Thomas - picked for Wales' Six Nations clash in Italy next week but allowed to play for his region on Saturday - broke through.
But diminutive scrum-half Peter Stringer bravely threw himself in the way and somehow managed to bump Thomas into touch at the corner flag.
Another Dragons try went begging when Wayne Evans burst through, only to be called back for Thomas tugging back a would-be Munster tackler.
Arlidge did earn some reward for a good spell of Dragons pressure with his third penalty, but Munster made sure with 15 minutes left when replacement Horgan stormed over for a converted try.
Dragons captain Tom Willis:
"We had plenty of ball and we put ourselves in some good areas on the field.
"But Munster are very good at dealing with pressure and when they get their chance they really know how to exert it.
"It was a difficult night in greasy conditions but we perhaps blew a couple of opportunities in the backs, but there were a couple of chances when the forwards could have used more vision and shifted the ball."
Munster captain Mick O'Driscoll:
"All credit to the Dragons, it's always a very tough place to come and for us to get a result here we're delighted.
"But the manner in which we played we're probably a little disappointed.
"It's very tight [in the Magners League table] obviously Leinster had a great win at the Ospreys and obviously we needed to win to go back on top."
Dragons: Jason Tovey; Kevin Morgan, Rory Sidey, Ashley Smith, Martyn Thomas; James Arlidge, Wayne Evans; Nigel Hall, Tom Willis (capt), Rhys Thomas, Sean Tomes, Andrew Hall, Joe Bearman, Richard Parks, Grant Webb.
Replacements: Steve Jones, Gethin Robinson for R Thomas (72), Lewis Evans for Webb (70), Danny Lydiate, Phillip Dollman, Gareth Maule for Arlidge (65), Robert Lewis for W Evans (65).
Munster: Denis Hurley; Kieran Lewis, Keith Earls, Lifeimi Mafi, Ciaran O'Boyle; Paul Warwick, Peter Stringer; Darragh Hurley, Denis Fogarty, Tony Buckley; Mick O'Driscoll (capt), Donnacha Ryan, Alan Quinlan, Denis Leamy, Nick Williams.
Replacements: Michael Essex, Timmy Ryan for Buckley (56), Billy Holland for Quinlan (71), Niall Ronan, Duncan Williams, Jeremy Manning, Anthony Horgan for O'Boyle (49).
Referee: Allan Lewis (Ireland).