Danny Barnes finished off a good Munster move in the 50th minute, Declan Cusack converting but Heriots refused to lie down and the introduction of replacement Marc Teague gave an already lively backline an added edge.
On two occasions the visitors spurned possible three pointers in favour of five metre line-outs and on each occasionthey came up short thanks mainly to the defensive efforts of Nick Williams and skipper Peter O'Mahony.
In the 70th minute Williams blocked down Teague's attempted clearance and gathered to score and in the closing stages replacement Sean Scanlon rounded off a good Munster backline move and showed good pace to score his side's fifth try that replacement Jeremy Manning converted.
Munster: Danny Riordan (Sean Scanlon 54 min); Danny Barnes, Mike Kelleher, Scott Deasy, Ciaran O'Boyle; Declan Cusack (Jeremy Manning 58 min), Duncan Williams (Conor Murray 74 min); Dave Kilcoyne (Pa O'Regan 74 min), Mike Sherry (Sean Henry 58 min), Stephen Archer; Dave Foley (Ed Kelly 74 min), Ian Nagle; Billy Holland (Neville Melbourne
58 min), Peter O'Mahony capt., Nick Williams.
Heriots: Colin Goudie; Jonny Alston, Peter Saunders, Richard Mill, Max Nimmo, Greig Rutherford, Graham Wilson capt; Alan Dymock, Scott Burnett, Wullie Blacklock; Philip O'Connor, Chukwuma Osazuwa; Peter Eccles, Chris Fusaro, Jamie Syme. Replacements: Finlay Gillies, Cameron Bruce, John-Patrick Ward, Neil Meikle, Marc Teague, Andrew Douglas, Michael Goldie