Retropharyngeal abscesses (RPA) are rare in adults. We report a case of a healthy adult with RPA presenting with clinical symptoms of acute thyroiditis. A 37-yr-old female presented with a painful mass in the anterior region of the neck, sore throat, mild fever and dysphagy for liquids and solids. Neck emergency US dis-closed normal thyroid ventrally displaced by a huge retropharyngeal hypoechoic mass. Direct laryngoscopy revealed erythema of the posterior pharyngeal wall with bulges (8 cm) preventing the correct visualization of the glottic plane. CT confirmed the pres-ence of retropharyngeal abscess and laryngoscopic drainage was performed. The pa-tient was discharged on 11th post-operative day, in good condition. The high mortality rate of retropharyngeal abscess is related to its association with invasion of contiguous structures and mediastinum: once mediastinitis occurs, mortality reaches 50%, even with antibiotic therapy. CT is fundamental for the diagnosis, but in many cases, as our, ultrasonography of the neck may play a pivotal role as quickly as possible. Surgi-cal treatment (intraoral incision and drainage) is the better definitive and resolutive treatment. The clinical diagnosis of retropharyngeal abscess in adult can be difficult because of the lacking and non specificity of clinical presentation. It is recommended to collect accurate clinical history, careful examination of the head and neck and use of early ultrasound examination of the neck, which in real time can give precise indications to guide the diagnosis and therapy. The management of a retropharyngeal abscess depends on the patient’s clinical condi-tion, moving from conservative treatment with steroids and antibiotics to reanimation and aggressive surgical drainage.