Objectives Chest X-ray (CXR), abdominal ultrasound, cardiac ultrasound, and abdominal X-ray are the most frequently used imaging modalities to radiologically evaluate patients with penetrating torso trauma. The aim of this study was to evaluate the accuracy of these imaging modalities. Methods From January 2001 until January 2005, all consecutive patients with penetrating torso injuries presenting at the emergency department of a level 1 trauma center were included. Imaging modalities (chest/abdominal X-ray, abdominal/cardiac ultrasound), were compared retrospectively with a 'gold standard' (i.e. computed tomography or surgery within 2 h after arrival) or outcome of conservative treatment. The accuracy of the imaging modalities was calculated. Results Three hundred and eighteen patients were included. On the basis of 299 CXRs, the sensitivity for diagnosing pneumothorax, hemothorax, and subcutaneous emphysema was 71, 63, and 61%, respectively. The sensitivity of abdominal ultrasound (N=229) to detect free abdominal fluid and/or intra-abdominal injury was 65%. The specificity, positive predictive value, negative predictive value, and accuracy of the two imaging modalities to detect any of the diagnoses mentioned were >=: 87%. Cardiac ultrasound (N=31) did not show any false positive or negative results for detecting cardiac effusion. Pneumoperitoneum was not seen on abdominal X-ray in eight of 11 patients with perforation of a hollow organ. Conclusion Despite high specificity, positive predictive value, and negative predictive value, a considerable number of lesions remain undetected after CXR and abdominal ultrasound because of moderate-to-inadequate sensitivity. Abdominal X-ray hardly provides additional information. Careful clinical monitoring of patients is mandatory, particularly when computed tomography scan or operative treatment is not indicated. European Journal of Emergency Medicine 16:305-311 (C) 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins.