Diagnostic upper gastrointestinal endoscopy is a very commonly performed procedure. Physicians use it as a safe diagnostic tool to evaluate patients with a wide range of problems and complaints, but it can cause several complications in few cases. Esophageal perforation is a rare complication of upper gastrointestinal endoscopy, but it is associated with a relatively high mortality rate. Surgical management is required in most such cases. However, medical treatment can be considered for selected patients who are without a large perforation or systemic effects such as sepsis. Deep neck abscess can develop in patients who have had difficult intubations, and this may be related to retropharyngeal trauma or unapparent perforations. We experienced a case of deep neck infection due to an esophageal perforation that developed as a complication of diagnostic upper gastrointestinal endoscopy, and we successfully treated this patient with incision and drainage.