BACKGROUND: The "seat belt sign" (SBS) has been reported to be highly associated with intra-abdominal injury. This study defines its predictive value in identifying injuries in a large pediatric trauma population. METHODS: At a level I pediatric trauma center, we performed a retrospective review of trauma flow sheets for all motor vehicle crash victims (ages, 0-20) requiring trauma team activation during 2005 and 2006. All patients with an abdominal SBS recorded were included in the analysis. RESULTS: Of 331 patients (mean age, 9.96 years), an SBS was present in 54 (16%) of these children. Abdominal injury was identified by computed tomography scan or intraoperatively in 12 (22%) of these children. Three (6%) children with SBS required operative intervention. Two had a bowel injuries and one had a negative laparoscopy. SBS and abdominal tenderness were reported in 30 (56%) patients; 8 (15%) of whom sustained abdominal injury. Of the 277 (84%) children without SBS, 36 (13%) had abdominal injuries. Four (11%) of these had a positive laparotomy with three having a bowel injuries. The relative risk of an abdominal injury given an SBS was 1.7 (CI 0.96-2.69; p = 0.078). Four (1.4%) children without SBS died of head injuries compared with zero with SBS. The SBS had a sensitivity of 25% and a specificity of 85%. CONCLUSIONS: The SBS was not significantly associated with abdominal injury in our population. Patients without SBS had a higher Injury Severity Score and accounted for all of the deaths. SBS may not be as predictive of abdominal injury as previously reported.