SummaryBackground: Penetrating trauma injury is generally associated with higher short-term mortality than blunt trauma, and results in substantial societal costs given the young age of those typically injured. Little information exists on the patient and treatment characteristics for penetrating trauma in England and Wales, and the acute outcomes and costs of care have not been documented and analysed in detail. Methods: Using the Trauma Audit Research Network (TARN) database, we examined patient records for persons aged 18+ years hospitalised for penetrating trauma injury between January 2000 and December 2005. Patients were stratified by injury severity score (ISS). Results: 1365 patients were identified; 16% with ISS 1-8, 50% ISS 9-15, 15% ISS 1624, 16% ISS 25-34, and 4% with ISS 35-75. The median age was 30 years and 91% of patients were men. Over 90% of the injuries occurred in alleged assaults. Stabbings were the most common cause of injury (73%), followed by shootings (19%). Forty-seven percent were admitted to critical care for a median length of stay of 2 days; median total hospital length of stay was 7 days. Sixty-nine percent of patients underwent at least one surgical procedure. Eight percent of the patients died before discharge, with a mean time to death of 1.6 days (S.D. 4.0). Mortality ranged from 0% among patients with ISS 1-8 to 55% in patients with ISS > 34. The mean hospital cost per patient was £7983, ranging from £6035 in patients with ISS 9-15 to £16,438 among patients with ISS > 34. Costs varied significantly by ISS, hospital mortality, cause and body region of injury. Conclusion: The acute treatment costs of penetrating trauma injury in England and Wales vary by patient, injury and treatment characteristics. Measures designed to reduce the incidence and severity of penetrating trauma may result in significant hospital cost savings.