Injuries are frequent occurrences in Rugby league. It is unclear, however, whether different age groups and grades have different patterns of injury. The frequency of injury in six grades of an elite rugby League Team were studied over a competitive season. There were 374 injuries suffered by 113 different players in 104 games totalling 1540 player-position hours. Minor injuries were the most common type reported, with the older teenage grades having the highest frequency. The Under 19 years team had the highest injury frequency at 405.6 injuries per 1000 player-position hours followed by the Under 17 years team with 343.2 injuries per 1000 player position hours. More severe injuries were most common in the senior grades. First grade players suffered a major or severe injury (resulting in missing at least one subsequent match) with a frequency of 41.2 injuries per 1000 player-position hours. Possible reasons for these differences include age related anthropometric differences, training levels and techniques, muscle mass and physical development, skill acquisition, psychological maturity, playing experience, physical fitness, coaching tactics and frequency of play.