The purpose of this study was to compare the outcomes of trauma patients with an Injury Severity Score (ISS) > 12 who had the trauma team involved (TTA) in their resuscitative care to those that did not (TTNA). Level I regional trauma center teaching hospital with university affiliation. All trauma patients admitted between July 1, 1991 and August 31, 1994 with an ISS > 12 were identified through the trauma registry. Burn patients, those who suffered their injury > 24 hours before admission, and deaths in the emergency room were excluded from analysis. The TRISS methodology, which offers a standard approval for evaluating outcomes for different populations of trauma patients, was used to determine whether there was a difference in outcomes between the two groups. To include patients who arrived at the trauma center intubated, a Trauma and Injury Severity Score (TRISS)-like analysis was also conducted on this patient population. A total of 640 patients were identified; 174 (65.2%) in the TTA group and 223 (34.8%) in the TTNA group. A total of 448 (70%) were eligible for TRISS analysis and 574 (89.7%) were eligible for TRISS-like analysis. Using the TRISS analysis, the TTA group had a Z statistic of 3.36 yielding a W score of 4.27. This compared to the TTNA group whose Z statistic was 0.30. Using the TRISS-like logistic regression equation, the TTA group had a Z statistic of 6.50, yielding a W score of 8.60 compared with the TTNA group whose Z statistic was 0.88. After controlling for differences in the demographics of the two groups, the TTA still had consistently higher Z scores. In a Level I trauma center, the outcomes of trauma patients with an ISS > 12 are statistically significantly better if the trauma team is activated than if the patients are managed on an individual service-by-service basis.