The physical preparation of team sport athletes should reflect the degree to which each component of fitness is relied upon in competition. The aim of the study was therefore to establish the relationship between fitness-test data and game behaviours known or thought to be important for successful play in rugby union matches. Fitness-test measures from 510 players were analysed with game statistics, from 296 games within the 2007 and 2008 calendar years. Sprint times over 10, 20 and 30 m had moderate to small negative correlations (r) with line breaks (~0.26), metres advanced (~0.22), tackle breaks (~0.16) and tries scored (~0.15). The average time of 12 repeated sprints and percentage body fat in the forwards, and repeated sprint fatigue in the backs had moderate to small correlations with a measure of activity rate on and around the ball (-0.38, -0.17 and -0.17, respectively). These low correlations are partly due to uniformly high physical fitness as a result of selection pressures at the elite level and leave room for the identification of other key predictors. Nonetheless, physical conditioning programmes should be adapted to reflect the importance of speed, repeated sprint ability and body composition in the performance of key game behaviours during competition.