Jeremy Manning opened the scoring with a penalty after three minutes but it was a short-lived lead as the home scored the game's opening try trough wing Shane Morahan after number 8 Ron Boucher had made the initial break.
However Munster's response was immediate. A series of scrums ended with them driving the Leinster eight - now without the injured Boucher - over the line and when skipper James Coughlan was impeded while grounding referee David Wilkinson upgraded the try to a penalty try making the conversion that bit easier for Manning.
A series of Munster errors, ending with a missed Manning tackle allowed wing Fionn Carr in under the posts, Ian Keatley's conversion leaving Leinster 12-10 in front but a further Manning penalty sent Munster in leading by one point at the break (13-12).
With the wind at their backs Munster totally dominated the second half, Leinster's only scoring opportunity coming from a Keatley penalty effort from the half way that, not surprisingly, fell short.
A neat passing movement started by Ian Dowling and carried on by the impressive Jake Paringatai and Mossy Lawlor ended in a try for Keith Earls in the 58th minute, Manning nailing a difficult conversion and further tries from replacement Tommy O'Donnell and the lively Tomas O'Leary with a minute to go gave Munster a deserved victory.
Munster A: Denis Hurley; Keith Earls, Barry Murphy (Mossy Lawlor 16th min), Conan Doyle (Gerry Hurley 50 min), Ian Dowling; Jeremy Manning (Barry Keeshan (62 min), Tomas O'Leary; Eugene McGovern, Denis Fogarty (Jerry Flannery 56th min), Tim Ryan (D arragh Hurley 56th min) ; Mark Melbourne, Donnacha Ryan; Jake Paringatai (T O'Donnell 62nd min), Niall Ronan (Billy Holland 62nd min), James Coughlan capt
Leinster A: Ross McCarron; Fionn Carr, Michael Berne, Kyle Tonetti, Felix Jones; Ian Keatley, Chris Keane; Ronan McCormack, Brian Blaney, Stephen Knoop; Devin Toner, Paul Huntley; Stuart Abbott, Stephen Rocket, Ron Boucher.