The Royal Marines regularly deploy to Norway to conduct Cold Weather, Arctic and Mountain Warfare training. A total of 1200 personnel deployed to Norway in 2010 over a 14-week period. Patients, whose injuries prevented them from continuing training, were returned to the UK via AEROMED. The aim of this investigation was to describe the epidemiology of musculoskeletal injuries during cold weather training. All data on personnel returned to the UK was prospectively collected and basic epidemiology recorded. 53 patients (incidence 44/1,000 personnel) were returned to the UK via AEROMED. 20/53 (38%) of cases were musculoskeletal injuries (incidence 17/1000 personnel). 15/20 musculoskeletal injuries were sustained while conducting ski training (incidence 13/1,000): 4/20 were non-alcohol related injuries, 1/20 was related to alcohol consumption off duty. Injuries sustained whilst skiing: 5/15 sustained anterior shoulders dislocation, 5/15 Grade 1-3 MCL/LCL tears, 2/15 sustained ACJ injuries, 1/15 crush fracture T11/T12, 1/15 tibial plateau fracture and 1/15 significant ankle sprain. Non-Training injuries: 1 anterior shoulder dislocation, 1 distal radial fracture, 1 olecranon fracture, 1 Scaphoid Fracture and one 5th metatarsal fracture. 60% of injuries were upper limb injuries. The most common injury was anterior shoulder dislocation 6/20 (Incidence 5/1000). Our results suggest that cold weather warfare training has a high injury rate requiring evacuation: 4% of all people deployed will require AEROMED evacuation, and 2% have musculoskeletal injuries. Ski training causes the majority of injuries, possibly due to the rapid transition from non-skier to skiing with a bergen and weapon. Military Orthopaedic and rehabilitation units supporting the Royal Marines, should expect sudden increases in referrals when large scale cold weather warfare training is being conducted. Further research is required to see if musculoskeletal injury rates can be decreased in cold weather warfare training