Rugby league is an international collision sport. Players complete physically demanding activities such as running, tackling and passing which often result in musculoskeletal injuries. Injury rates increase as playing level increases. From 1999 to 2007 there were 42,754 rugby league claims costing Accident Compensation Corporation $48,704,704. Moderate to severe injury claims (MSC) represented 14% of these claims but 88% of costs. New Zealand Maori recorded significantly more injury claims and total injury entitlement costs than all other ethnic groups. Soft tissue MSC injuries were common (47%) for females. Concussions accounted for 70% of total rugby league injuries to the head while the knee represented 23% of total injury claims and 20% of injury costs. Neck and spine injuries accounted for 6% of total MSC injury claims but 16% of total MSC costs. In video analysis of 80 games at international, national and youth competition levels, 50% of tackles involved tacklers from behind the visual fields of the ball carrier, either two or three tacklers, and contact with the mid-torso or hip-thigh region. From the prospective injury analysis of one professional team over two consecutive years, tackle-related injuries occurred more to the ball carrier when tackled at shoulder or mid-torso height, in their blind vision, with two or more tacklers, and in the fourth quarter of matches. Tackle-related injury type and site varied by positional group. Hit-up forwards and outside backs recorded more tackle-related injuries as the ball carrier than the tackler. In the prospective study of 63 amateur rugby league players, 80% of players injured as a result of match or training activities saw a health professional as part of their rehabilitation. Team coaches asked players to return to rugby league activities in 28% of cases for training participation and 29% of cases for match participation. In the cross sectional study assessing 95 rugby league support personnel's first aid, injury prevention and concussion knowledge, only 2% achieved an 80% pass mark, 39% incorrectly stated loss of consciousness was required for concussion and only 24% of coaches had a rugby league coaching qualification. This PhD research has contributed knowledge regarding costs and characteristics of injuries to amateur rugby league participants analysed by ethnicity, gender, injury site and injury type. Changes in anthropometric characteristics and speed in regards to incidence of injury, characteristics of tackles in match situations and common tackling positions and positional groups where injuries occur, player perspectives on why they return from injury to participation in rugby league, and the lack of first aid knowledge for rugby league personnel, have all been described.