The presence of a surgeon at the initial assessment and care of the trauma patient has been the focal point of trauma center designation. However, for Level I verification, the American College of Surgeons Committee on Trauma currently does not require the presence of an attending trauma surgeon in the hospital (IH), provided senior surgical residents are immediately available. Likewise, the state of Missouri does not mandate an IH presence of the attending trauma surgeon but requires senior (postgraduate year 4 or 5) level surgical residents to immediately respond, with a 20-minute response time mandated for the attending surgeon if IH or out of the hospital (OH). Nevertheless, some claim that IH coverage by attending surgeons provides better care for seriously injured patients.This retrospective study assessed patient care parameters over the past 10 years on critically injured patients to detect any difference in outcome whether the surgeon was IH or OH at the time of the trauma team activation (cardiopulmonary instability, Glasgow Coma Scale [GCS] score 15, or ISS > 25. Response was examined from 8 am to 6 pm weekdays (IH) or 6 pm to 8 am weekdays and all weekends (OH). Patient care parameters examined were mortality, complications, time in the emergency department, time to the operating room, time to computed tomographic scanning, intensive care unit length of stay (LOS), and hospital LOS.For all patients (n = 766), there was no significant difference in any parameters except intensive care unit LOS (IH, 4.90 +/- 7.96 days; OH, 3.58 +/- 7.69 days; p 15 (n = 363), and ISS > 25 (n = 230), there were no statistically significant differences in any patient care parameter between IH and OH response. For those in most need of urgent operation-penetrating injuries and shock-there were no differences in time to operating room or mortality for OH or IH response.As long as initial assessment and care is provided by senior level IH surgical residents and as long as the attending surgeon responds in a defined period of time (if OH) to guide critical decision-making, the IH presence of an attending surgeon has not been shown in this retrospective study to improve care of the critically injured patient.