Odontogenic infections are a normally locally confined, self-limiting process that is easily treated by antibiotic therapy and local surgical treatment. However, it may spread into the surrounding tissues through a perforation of the bone, and into contiguous fascial spaces or planes like the primary or secondary fascial spaces. If the infection extends widely, it may spread into the lateral pharyngeal and retropharyngeal space. The retropharyngeal space is located posterior to the pharynx. If an odontogenic infection spreads into this space, severe life-threatening complications will occur, such as airway obstruction, mediastinitis, pericarditis, pleurisy, pulmonary abscess, aspiration pneumonia and hematogenous dissemination to the distant organs. The mortality rate of mediastinitis ranges from 35% to 50%. Therefore, a rapid evaluation and treatment are essential for treating retropharyngeal space abscesses and preventing severe complications. Recently, we encountered two cases of a retropharyngeal space abscess due to the spread of an odontogenic infection. In all patients, early diagnosis was performed by computed tomography scanning and a physical examination. All patients were treated successfully by extensive surgical and antibiotic therapy.