Objective:To determine the patterns of oxygen consumption (&OV0312;O2) using indirect calorimetry (IC) for the first 24 hrs after serious blunt traumatic injury.Design:Prospective, observational study.Setting:Surgical intensive care unit of a Level 1 trauma center.Patients:Sixty-six mechanically ventilated patients with blunt traumatic injury and Injury Severity Score >15.Interventions:IC for 24 hrs postinjury. Patients were resuscitated to standard parameters of perfusion.Measurements and Main Results:Mean patient age was 50.1 ± 18.7 yrs with a mean Injury Severity Score 30.7 ± 11.3). Mean &OV0312;O2for all patients for the 24-hr study period was 168.5 ± 29.5 mL/min/m2. The level of &OV0312;O2was not related to Injury Severity Score, the number or combination of organ systems injured, or to the use of vasoactive agents. Patients >65 yrs of age had significantly lower &OV0312;O2(p= .0038) compared with patients ≤50 yrs. &OV0312;O2did not change over time after resuscitation to normal parameters of perfusion. Mean &OV0312;O2was 156.5 ± 63.2 mL/min/m2in patients who developed multiple organ dysfunction, and 172.4 ± 33.3 mL/min/m2in those who did not develop multiple organ dysfunction (p= .16).Conclusions:Seriously injured patients are hypermetabolic in the early postinjury period. The level of &OV0312;O2is unrelated to injury severity or number of organ systems involved. Elderly patients can be expected to have lower levels of &OV0312;O2. &OV0312;O2does not change significantly in response to resuscitation to normal parameters of perfusion. &OV0312;O2measured by IC did not predict the development of multiple organ dysfunction.