Background: Thoracic trauma is commonly treated with tube thoracostomy. The overall complication rate associated with this procedure is up to 30% among all operators. The primary purpose of this study was to define the incidence and risk factors for complications in chest tubes placed exclusively by resident physicians. The secondary objective was to outline the rate of complications occult to postinsertional supine anteroposterior (AP) chest radiographs (CXRs). Methods: Over a 12-month period at a regional trauma centre, we retrospectively reviewed all severely injured trauma patients (injury severity score > 12) who underwent tube thoracostomy (338/761 patients). Insertional, positional and infective complications were identified. Patients were assessed for complications on the basis of resident operator characteristics, patient demographics, associated injuries and outcomes. Thoracoabdominal CT scans and corresponding CXRs were also used to determine the rate of complications occult to postinsertional supine AP CXR. Results: Of the patients, 338 (44%,) had CXR and CT imaging. Out of 76 (22%) chest tubes placed by residents in 61 (18%) patients (99% of whom had blunt trauma injuries), there were 17 complications; 6 (35%) were insertional; 9 (53%) were positional and 2 (12%) were infective. Tube placement outside the trauma bay (p = 0.04) and nonsurgical resident operators (p = 0.03) were independently predictive of complications. The rates of complications according to training discipline were as follows: 7% general surgery, 13% internal and family medicine, 25% other surgical disciplines and 40% emergency medicine. Resident seniority, time of day and other factors were not predictive. Six of 11 (55%) positional and intraparenchymal lung tube placements were occult to postinsertional supine AP CXR. Conclusions: Chest tubes placed by resident physicians are commonly associated with complications that are not identified by postinsertional AP CXR. Thoracic CT is the only way to reliably identify this morbidity. The differential rate of complications according to resident specialty suggests that residents in non-general surgical training programs may benefit from more structured instruction and closer supervision in tube thoracostomy.</p