Differential diagnosis of posterior neck pain is very challenging based on symptoms and physical examination only. Retropharyngeal calcific tendinitis is a rare and frequently misdiagnosed entity in various causes of neck pain. It results from calcium hydroxyapatite deposition in the longus colli muscle which is characterized by severe neck pain, painful restriction of neck movement, dysphagia, and odynophagia. We herein report a case of a patient with acute retropharyngeal calcific tendinitis, who complained of posterior neck pain, initially diagnosed and treated as a myofascial neck pain syndrome.