Descending necrotizing mediastinitis (DNM) is a complication of odontogenic or oropharyngeal infections that can spread to the mediastinum. Such infections is serious, leading to sepsis and frequently to death. Even in this era of antibiotics, the mortality rate associated with DNM is approximately 40%. It is difficult to diagnose early because clinical and radiologic findings appear in the late stage of the infection. Delayed diagnosis is the principal reason for the high mortality in DNM. Therefore, descending necrotizing mediastinitis requires an early and aggressive surgical approach to reduce the high morbidity and mortality associated with this disease. We experienced a case of odontogenic infection followed by acute mediastinitis, so present now with the review of literatures.