This study evaluated whether the judogi colour (blue or white) could influence a combat outcome (victory or defeat) in 1,233 judo official combats. Sex, age group, and level of competition were also considered in the analysis. Binomial probability tests showed a higher probability of an athlete's winning a combat wearing blue judogi for both sexes, levels of competition (regional and state), and for the athletes of the junior and senior categories. Thus, blue judogi may bias competitive outcome for both sexes in regional and state level competitions and for athletes above junior age.