Just as data from civilian trauma registries have been used to benchmark and evaluate civilian trauma care, data contained within the Joint Theater Trauma Registry (JTTR) present a unique opportunity to benchmark combat care. Using the iterative steps of the benchmarking process, we evaluated data in the JTTR for suitability and established benchmarks for 24-hour mortality in casualties with polytrauma and a moderate or severe blunt traumatic brain injury (TBI). Mortality at 24 hours was greatest in those with polytrauma and a severe blunt TBI. No mortality was seen in casualties with polytrauma and a moderate blunt TBI. Secondary insults after TBI, especially hypothermia and hypoxemia, increased the odds of 24-hour mortality. Data contained in the JTTR were found to be suitable for establishing benchmarks. JTTR data may be useful in establishing benchmarks for other outcomes and types of combat injuries.