The 2018 World Rugby U20 Trophy was the eleventh annually held international rugby union competition for Under 20 national teams, with host nation Romania, along with seven other sides, playing in a group stage followed by a knockout round to determine a champion as well as promotion to the following years' World Rugby Under 20 Championship.
A total of eight teams played in the tournament. Other than the host nation of Romania and Samoa who were relegated following the 2017 World Rugby Under 20 Championship, six nations qualified through their respective regional qualifiers.