Leinster (3) 13
Try: O'Driscoll Pens: Nacewa 2 Con: Nacewa
Munster (3) 9
Pens: O'Gara 3
Brian O'Driscoll's try was the crucial score in Leinster's vital win
Brian O'Driscoll's late try helped Leinster end Munster's unbeaten start to the Magners League as the home side earned a morale-boosting win.
The sides were level at 3-3 at half-time with Isa Nacewa cancelling out a Ronan O'Gara penalty.
Two O'Gara penalties nudged Munster 9-6 ahead but Sean O'Brien set up O'Driscoll's decisive 70th-minute try.
New Leinster coach Joe Schmidt had gone into the game under some pressure after his team's poor start to the season.
Three defeats in their opening four games left Leinster near the foot of the table but as many predicted, they pulled out a big performance against their Irish rivals.
A geed-up Munster won the early collisions, and a quick turnover led to a fourth-minute penalty which O'Gara converted from inside the 22.
Munster centres Lifeimi Mafi and Sam Tuitupou produced some purposeful runs but Leinster's defence stood up to the visitors' opening barrage.
Nacewa then conjured up the game's first real line-break and Munster were forced to concede a penalty which the fly-half landed from in front of the posts.
Johne Murphy went close to scoring a Munster try before the break but the ball just beat him to touch after he had hacked on a chip through from Tomas O'Leary.
After half-time, Mafi was sin-binned after a high tackle on Rob Kearney but O'Gara kicked the 14 men back in front after Gordon D'Arcy had transgressed at a ruck.
A trademark run and offload from O'Driscoll yielded a successful penalty for Nacewa but O'Gara edged Munster ahead again after hands in the ruck from Strauss.
The game was there for the taking and Schmidt's side stepped up to the mark, pinning Munster back as they began to make better use of possession.
O'Leary had to put a try-saving tackle in on O'Brien after a jinking run from Kearney.
With time running out, the impressive O'Brien burst past Paul Warwick and threw a backhanded pass out of the tackle for the supporting O'Driscoll to run in from the right.
Nacewa added the extras and the four-point gap was enough to see Leinster complete their first five in-a-row over Munster since the 1930s.
Leinster: R Kearney; S Horgan, B O'Driscoll, G D'Arcy, L Fitzgerald; I Nacewa, I Boss; C Healy, R Strauss, M Ross, N Hines, D Toner, D Ryan, S O'Brien, J Heaslip (capt).
Replacements: J Sexton for Horgan 56, E Reddan for Boss 56, H van der Merwe for Healy 61, S Shawe for Ross 77, RRuddock for Heaslip 77.
Not Used: J Harris-Wright, M Galarza, F McFadden.
Munster: P Warwick; D Howlett, L Mafi, S Tuitupou, J Murphy; R O'Gara, T O'Leary; W du Preez, D Varley, J Hayes; D O'Callaghan, D Ryan; A Quinlan, N Ronan, D Leamy (capt)
Replacements: M Horan for du Preez 64, M O'Driscoll for D Ryan 64.
Not Used: S Henry, D Hurley, D Wallace, P Stringer, S Deasy, D Hurley.
Referee: J Garces (France)