Descending necrotising mediastinitis is a terrible disease, usually a complication of an inflammatory process of the pharynx, pathology of themandibular or submandibular space. The development of mediastinitis in a patient after haemithyroidectomy under general anaesthesia withtracheal intubation due to esophagus injury is a very rare condition. Our patient’s early post-operative period was complicated by severe painbehind the sternum not associated with acute coronary syndrome. On the second post-operative day, our suspicions of mediastinitis were notdefinitively supported by diagnostic tests. On the fourth post-operative day, the patient experienced septic shock, necessitating emergentrepeated oesophagogastroduodenoscopy, which located the injury of oesophagus. Emergent torachotomy for mediastinitis, gastrostomy andmediastinal drainage was conducted on the fourth post-operative day. Despite aggressive surgical and critical care management, the patient died3 days after. Death was caused by mediastinitis complicated by severe sepsis and multiple organ failure. On autopsy, the damage to the posteriorwall of the oesophagus occurred as a result of penetrating trauma to cervical and thoracic spine osteophytes during hemithyroidectomy. Thepathology section revealed that acute angle osteophytes located at the cervical level injured the oesophagus when the pressure was applied inremoving part of the thyroid gland with malignant neoplasia.