Background: Improvised explosive devices (IEDs) pose a significant threat to military personnel, often resulting in lower extremity amputation and pelvic injury. Immediate management is haemorrhage control and debridement, which can involve lengthy surgery. Computed tomography is necessary to delineate the extent of the injury, but it is unclear whether to perform this during or after surgery. Methods: The UK Joint Theatre Trauma Registry was searched to identify all UK service personnel who had a traumatic lower extremity amputation following IED injury between January 2007 and December 2010. Data were collected on injury pattern and survival. Results: There were 169 patients who sustained 278 traumatic lower extremity amputations: 69 were killed in action, 16 died from their wounds and 84 were wounded in action, but survived. The median (interquartile range) Injury Severity Score was 75 (21) for those killed in action, 46 (23) for those who died from wounds and 29 (12) for survivors. There were significantly more severe head, chest and abdominal injuries (defined as a body region Abbreviated Injury Scale score of 3 or more) in patients who were killed in action than in those reaching hospital (P < 0·001). Hindquarter amputations were the most lethal, with a mortality rate of 95 per cent. Of the 100 casualties who reached hospital alive, there were nine thoracotomies, one craniotomy and 34 laparotomies. All head or torso injuries that required immediate operation were clinically apparent on admission. Conclusion: Higher levels of amputation were associated with greater injury burden and mortality. Intraoperative computed tomography had little value in identifying clinically significant covert injuries.