A thoracic infection originating in the oropharynx is reviewed in the light of anatomical pathways and bacteriology. Simple sore throat was followed by extensive neck swelling causing airway obstruction and necessitating an emergency tracheotomy. The retropharyngeal fascial space served as a route for the spread of an overwhelming infection along cervical planes into the mediastinum and both pleural cavities. The offending organism was identified as a gas-producing Bacteroides. Despite massive antibiotic therapy, tracheotomy, and surgical drainage of both the retropharyngeal space and the pleural cavity, the patient died.