This study aims to identify predisposing characteristics of descending necrotizing mediastinitis (DNM) arising from deep neck infection (DNI) and to determine appropriate therapeutic intervention strategies. We retrospectively reviewed 54 patients (male, n = 34; female, n = 20; mean age, 64.5 years) who had been treated at Mie University Hospital for DNI between April 2001 and October 2011. Eight of nine patients who developed DNM confirmed by computed tomography of the neck and chest, underwent mediastinal drainage (video-assisted thoracic surgical drainage, n = 6; mediastinoscopy-assisted drainage, n = 2). A patient developed uncontrolled acute respiratory distress syndrome after aggressive surgery, resulting in a mortality rate of 12 %. High blood CRP values, and the pharynx and tonsils as origins of infection were factors involved in the development of DNM arising from DNI. In conclusion, DNM remains a destructive and fatal disease that requires aggressive treatment including mediastinal exploration.