Pharyngeal foreign bodies are quite common. Their diagnosis is usually easy. The risk of complications including retropharyngeal abscess and mediastinitis is rare and it depends mainly on the nature of the foreign body and the period of the therapeutic management. The occurrence of these complications darkens the prognosis of this affection usually benign. We report a 21 years old patient, without any significant history, admitted to the emergency for a high painful dysphagia and impaired general condition with fever 20 days after trauma in the posterior pharyngeal wall following a meal. The radiological assessment including cervico-thoracic CT scan had objectified the presence of a metallic foreign body in the retropharyngeal space associated with a retropharyngeal abscess and aggravated by a mediastinitis following the migration of the foreign body to the chest. Biological markers of infection were very increased. The therapeutic management consisted of a surgical drainage of the collections by a cervicotomy with removal of the foreign body. The outcome was favorable clinically and biologically. Pharyngeal foreign bodies are common and favorable when the diagnosis and extraction are made on time. The occurrence of complications, especially retropharyngeal abscess and mediastinitis is rare and burdened with a high morbidity and mortality.