Leinster looked the stronger side in the opening half setting the tempo with quick lineouts and making the Munster defence work hard.
After 20 minutes number 4 Eoin Sheriff made it over the line for the first try of the evening, converted by centre Fergus McFadden.
Leinster continued the attack when winger Dave Kearney made a break down the left hand side just to be stopped on the Munster 22 by local man Dave Foley.
McFadden missed out on two subsequent penalty chances and Munster got to within a point going into the final minutes of the first half with two penalties kicked by outhalf Declan Cusack.
The latter penalty offence also resulted in a yellow card for Leinster number 7 Dominic Ryan on the 40th minute.
Leinster led 7-6 going in at the break and both teams had everything to play for going into the final 40 and with the opposition a man down Munster needed to take full advantage.
On the return Munster captain James Coughlan found a gap in the Leinster defence, setting the pack forward and Munster began to build the phases.
The Leinster defence held strong, making the Munster forwards pick and go for several phases. Munster continued to press on and they were rewarded for their patience and control when prop David Kilcoyne found his way over the try line, with Cusack adding the points.
Leinster responded with a McFadden penalty bringing it to 13-10 after 55 minutes.
Munster continued to make strides when keeping the ball in tight and recycling the possession, and forced a Leinster infringement and another 3 points from Cusack.
A Munster error in play rewarded Leinster with an easy try as winger Michael Keating ran in unopposed to bring Leinster within a point going into the final quarter.
Anthony Foley made the changes with Sean Henry, Peter O'Mahony and Simon Zebo coming on in the 65th minute and the forward momentum continued with Munster getting the final score of the night with a Billy Holland try.
The Leinster youngsters continued to attack the Munster line in the final minutes but the homeside withheld the pressure and did just enough to hold on to the 21-15 lead.
Munster: Danny Riordan, Ronan O'Mahony (Simon Zebo 65mins), Tom Gleeson, Scott Deasy, Danny Barnes, Declan Cusack, Duncan Williams, Dave Kilcoyne, Mike Sherry (Sean Henry 65mins), Stephen Archer, Dave Foley, Donnacha Ryan, Billy Holland, Tommy O'Donnell (Peter O'Mahony 65mins), James Coughlan capt. Replacements: Sean Henry, Pa O'Regan, Kieran Essex, Peter O'Mahony, Paul Rowley, Andrew Burke, Simon Zebo.
Leinster: Niall Morris, Michael Keating, Fergus McFadden, Kyle Tonetti, David Kearney, Ian McKinley, Paul O'Donohoe, Jack McGrath, Jason Harris-Wright, Stewart Maguire, Eoin Sheriff, Mark Flanagan, Rhys Ruddock, Dominic Ryan, Paul Ryan Replacements: Tom Sexton, Ben Barclay / Jack O'Connell, Ciaran Ruddock, Jordi Murphy, David Moore, Brendan Macken, Andrew Conway