PURPOSE: To analyse the causes and radiologic findings in patients with mediastinitis and to evaluate theefficacy of chest CT scanning in patients with delayed diagnosis. MATERIALS AND METHODS: Seventeen patients withhistopathologically(n=15) or cliniclly diagnosed(n=2) mediastinitis were involved in this study. Eleven of theformer group underwent surgery, and in four, tube drainage was performed. All underwent chest radiography and CTscanning, and in seven patients, the causes of delayed diagnosis were analysed. RESULTS: The most common cause ofmediastinitis was esophageal rupture (n=11). Others were extension from neck abscess to the mediastinum(n=3),complications after a Benthall procedure(n=1), tuberculous lymphadenitis (n=1) and mycotic aneurysm(n=1). Patientswith esophageal rupture suffered from underlying diseases such as esophageal cancer(n=2), iatrogenic esophagealrupture(n=2), Boerhaave's syndrome(n=2), and esophagitis(n=1). In patients with neck abscess(n=3), each wassecondary to infected cystic hygroma, Ludwig angina, or deep neck infection, respectively. On chest CT, patientswith esophageal rupture(n=11) had an abscess in the posterior mediastinum; nine abscesses extended to the cervicalarea along the retropharyngeal space, and the patient with Ludwig angina had an abscess involving all compartmentsof the mediastinum. Among the total of 17 patients, diagnostic delays were found in seven, while five hadspontaneous esophageal ruptures and two suffered complications after a Benthall procedure and Tbc lymphadenitis,respectively. The causes of diagnostic delay varied. Among seven patients, pnevmonia was initially diagnosed intwo, who were treated ; one had multiorgan failure, and one was suffering from pericardial effusion and lungabscess. In three other patients, chest radiographs initially showed non-specific findings, leading to delayed CTexamination. CONCLUSION: The most common cause of mediastinitis was esophageal rupture, and in these patients,chest radiographs and clinical symptoms were sometimes not specific. CT was valuable for the detection ofmediastinitis, and for early diagnosis can be the modality of choice.