Trauma patients are thought to be at high risk for iatrogenic retained foreign bodies (RFBs). The objective of this study was to evaluate this incidence. All cases of RFB after cavitary trauma surgery were identified by review of Morbidity and Mortality reports at a Level 1 trauma center from January 1998 to December 2005 and confirmed by the Octagon Risk Management System. Over 8 years, 10,053 trauma operations were performed (2075 laparotomies, 377 thoracotomies, and 74 sternotomies). Three cases (0.1%) of RFB (all sponges) occurred during one single-stage and two damage control laparotomies. The counts were correct before definitive closure in two of three cases. No postoperative x-rays were obtained in any of the cases. RFB diagnosis occurred between days 3 and 9, one on a routine chest x-ray and the other two on abdominal computed tomography scans during a septic workup. Four-month to 8-year follow up documented one pleural effusion and one abscess resulting from the RFB. Iatrogenic RFBs after emergent cavitary trauma surgery occur at a rate of 0.12 per cent and are associated with significant morbidity. In addition to standard preventive strategies, in emergent cases with risk factors such as requiring damage control, before final cavity closure, even with a correct sponge count, radiographic evaluation is warranted.