Davide Passini won the game for the visitors with a last minute penalty from the Munster 22.
The deadlock was broken in the 10th minute when Tomas Quinlan got a try in the corner for the home side, but this was promptly cancelled out when Matteo Archetti was credited with a pushover try from a driving maul deep in the Munster 22 for the visitors.
Quinlan put Munster ahead with a penalty midway through the opening half, but the Italians took the lead for the first time when Adriano Daniele made a break from a maul deep in the home side's 22 for a try which was converted by Filippo Cantoni.
Winger Eoin O'Carroll put the home side back in the driving seat when he sprinted from his own 22 to crash over in the corner to give Munster a 13-12 interval lead.
Munster stretched their advantage to eight points with a try by Steven McMahon which was converted by Quinlan, but Italy responded with a try from Passini.
Quinlan converted a penalty for the home side with ten minutes remaining, but Luca Squarbossa got a try for the visitors to leave a single point between the sides before Passini last minute penalty.
Scorers: Munster: Tomas Quinlan try, conversion & 2 penalties; Eoin O'Carroll & Steven McMahon tries.
Italy: Davide Passini try & penalty; Matteo Archetti, Matteo Archetti & Luca Squarbossa tries, Filippo Cantoni conversion.
Munster U19 XV: Stephen Fitzgerald (Ard Scoil Ris), Eoin O'Carroll (Tralee), Steven McMahon (Rockwell), JJ O'Neill (Crescent College), Brion Moriarty (Ard Scoil Ris), Tomas Quinlan (CBC), David O'Mahony (Rockwell), Liam O'Connor (CBC), Sean McNulty (Rockwell), Brendan Quinlan (Rockwell), Frank Bradshaw Ryan (Ard Scoil Ris), Aaron Hogan (Youghal), Jonathon Keane (Crescent College), Luke O'Leary (Sunday's Well), Ben Kilkenny (St. Munchins). Replacements: Denis O'Connell (Rockwell), Jack Boland (Glenstal), Mike O'Donnell (Crescent College), Dylan Lane (PBC), Cormac Blake (Crescent College), Jack Cullen (Exile), Dylan Horgan (Highfield), Shane McAuliffe (CBC).
Italy: Gabrielle Di Giulio; Lorenzo Crotti, Simone Balocchi, Matteo Gabbianelli, Filippo Lombardo; Filippo Cantoni, Simone Parisotto; Paolo Buonfiglio, Adriano Daniele, Patrick Bigoni; Frederico Ruzza, Davide Zanetti; Michele Boccardo, Matteo Archetti, Matteo Cornelli.
Replacements: Davide Passini & Luca Squarbossa