BACKGROUND Penetrating thoracic injuries are a common presentation in Emergency Departments in South Africa with pneumothorax, haemothorax and haemopneumothorax (PTX/HTX/HPTX) a cause of morbidity and mortality. Serial chest X-rays (CXRs) are used to assess patients with penetrating thoracic injury without PTX/HTX/HPTX on initial CXR in order to increase sensitivity and thus detection of PTX/HTX/HPTX. This study aimed to assess the utility of serial CXRs to detect a delayed presentation of PTX/HTX/HPTX following penetrating thoracic injury. METHODS This retrospective observational study analysed data from Helen Joseph Hospital Emergency Department, Johannesburg, South Africa for patients presenting with penetrating thoracic injury over a 2-year period for whom the initial CXR was negative for a PTX/HTX/HPTX to determine the utility of serial CXRs for detection of a delayed presentation of PTX/HTX/HPTX. RESULTS 118 patients, the majority of which had penetrating trauma secondary to a stab wound, were included in the study. Eight (7%) had a PTX/HTX/HPTX detected on subsequent investigation. Three (3%) patients with normal initial CXRs and three (3%) patients with abnormal initial CXRs had a PTX/HPX/HPTX detected on serial CXRs. Two (2%) delayed presentations of PTX/HTX/HPTX were noted on computerised tomography (CT) scan only. Six patients had an intercostal drain (ICD) inserted and were admitted; 2 patients (those with PTX/HTX/HPTX noted on CT only) were managed conservatively. Three patients (3%) had an ICD inserted to manage a delayed presentation of PTX/HTX/HPTX with a normal initial CXR. CONCLUSIONS Only 3% of patients with normal initial CXRs required intervention. CONCLUSIONS It is recommended that patients for whom the presentation CXR shows an abnormality undergo serial CXRs. Given the low incidence of PTX/HTX/HPTX in patients with a normal presentation CXR, along with the resource implications of serial CXRs, it may be prudent to discharge patients with thorough counselling and advice to return for review if warranted.