This chapter discusses deep neck infections, where the entire neck is compartmentalised in order to separate all the vital areas to prevent spread of infection. Pharynx is provided with cushion effect of various parapharyngeal, retropharyngeal and other spaces. The cervical fascia is a fibrous connective tissue enveloping neck muscles and neurovascular bundles creating potential neck spaces. Prestyloid compartment contains loose areolar tissue and internal maxillary artery. The retropharyngeal space lies between the prevertebral fascia and the buccopharyngeal fascia extending from base of skull to mediastinum. Mediastinitis may occur along the carotid sheath. Antibiotic therapy is usually aimed at gram-positive organisms, with appropriate modification based on the clinical situation and culture results. Common causes of parapharyngeal abscess are by spread of infection from tonsils, teeth injuries, and trauma such as penetrating injuries or iatrogenic injuries. Tracheostomy may be required in case of mechanical obstruction to the airway due to large abscess or laryngeal oedema.