Ireland beat Italy in their final Pool B game at the World Junior Championship in South Africa but were pipped by the Springboks for a semi-final place.
The Irish had beaten the hosts and lost to England in their opening fixtures.
Ireland led 24-12 at half-time, with Peter Nelson, Aaron Conneely and Chris Farrell scoring tries.
Nelson, James Rael and Luke McGrath added touchdowns in the second period, while Jack Carty contributed a total of one penalty and three conversions.
Carty was off-target with two other conversion attempts.
Italy scored all their points in the first half, with Edoardo Padovani converting his own try and Guido Calabrese crossing the line for his side's second try.
South Africa later beat England to clinch their semi-final spot by one point.
The hosts edged through to the last four by virtue of earning a four-try bonus point against the English.