Gabbett, TJ. Relationship between accelerometer load, collisions, and repeated high-intensity effort activity in rugby league players. J Strength Cond Res 29(12): 3424–3431, 2015—Triaxial accelerometers have been critical in providing information on the high-acceleration, low-velocity movements that occur in team sports. In addition, these sensors have proven to be useful in quantifying the activities that do not involve the vertical acceleration associated with locomotion (e.g., tackling, on-ground wrestling, and grappling). This study investigated the relationship between Player Load (PL), 2D Player Load (2DPL), and Player Load Slow (PL Slow), collisions, and repeated high-intensity effort (RHIE) activity in rugby league players. One hundred and eighty-two rugby league players (age, 24.3 ± 3.3 years) participated in this study. Movement was recorded using a global positioning system unit sampling at 10 Hz and triaxial accelerometer sampling at 100 Hz. Analysis was completed during 26 matches (totaling 386 appearances). Pearson product-moment correlation coefficients were used to determine relationships between PL, 2DPL, and PL Slow and total collisions and RHIE activity. When all players were considered, weak relationships were found between PL and the number of collisions and RHIE bouts performed. However, PL was strongly associated (p ≤ 0.05) with total distance, low-speed activity, high-speed running distance, total collisions, and the number of RHIE bouts for forwards and hookers. Weak and typically insignificant relationships were found between PL, 2DPL, and PL Slow and the number of collisions and RHIE bouts performed by the adjustables and outside backs positional groups. The relationships between PL and the number of collisions and RHIE bouts are stronger in positions where contact and repeated-effort demands are high. From a practical perspective, these results suggest that PL, 2DPL, and PL Slow offer useful “real-time” measures of collision and RHIE activity, particularly in forwards and hookers, to inform interchange strategies and ensure players are training at an adequate intensity.