['Combat sport athletes acutely reduce body mass (BM) prior to weigh-in in an attempt to gain a size/strength advantage over smaller opponents. Few studies have investigated these practices among boxers and none have explored the impact of this practice on competitive success.', 'One hundred (30♀/70♂) elite boxers participating in the Australian National Championships were weighed at the official weigh-in and an hour before each competition bout. Re-gain in BM after weigh-in was compared between finalists and non-finalists, winners and losers of each fight, males and females and weight divisions. Boxers were surveyed on their pre and post weigh-in nutrition practices.', 'The lightest male weight category displayed significantly greater relative BM re-gain than all other divisions, with no difference between other divisions. BM pre-bout was higher than official weigh-in for males (2.12±1.62% (p < 0.001; ES=0.13)) and females (1.49±1.65% (p < 0.001; ES=0.11)). No differences in BM re-gain were found between finalists and non-finalists, winners and losers of individual bouts, or between preliminary or final bouts. BM re-gain was significantly greater (0.37% BM, p < 0.001; ES=0.25) prior to an afternoon bout compared to a morning bout.'] Is weight Re-Gain Linked to Success in a Real Life Multi-Day Boxing Tournament?