Deep neck infection is not difficult to diagnose clinically, but correct localization of the involved space for timely incision and drainage is not easy without assistance of imaging. To investigate the images of deep neck space infection of phlegmon and abscess and the role of imaging examination in correct localization and treatment. Between June 2004 and June 2010, 28 patients were diagnosed with deep neck infection (14 men, 14 women; age range, 17-72 years; mean age, 46 years). Clinical presentations included neck swelling, pain, dysphagia, fever, and elevated white blood cell count. Of the 28 cases, 20 had computed tomography (CT) scans, 18 had magnetic resonance imaging (MRI) examinations, and 10 had both CT and MRI. All 28 patients were confirmed by CT and/or MRI to have deep neck infection, with 11 cases in the retropharyngeal space, five in the parapharyngeal space, four in the masseteric space, and eight in multiple spaces. Thirteen cases had abscesses that were successfully treated with incision and drainage under CT guidance in combination with large doses of antibiotics, and 15 had phlegmon managed with large doses of antibiotics. Followed up for 5-20 months, all patients recovered completely. Two patients were confirmed by imaging examination to have retropharyngeal infection spreading to the superior mediastinum with abscess formation and another two patients had multiple space infection because inappropriate puncture or incision for drainage without imaging guidance in these patients caused the spread of infection. Clinical diagnosis was not accurate with only 12 patients (42.9%) being correctly diagnosed of the exact deep neck space involved before imaging confirmation. CT and/or MRI made the correct diagnosis in all 28 patients. CT and/or MRI also directly changed the treatment plan in seven patients and contributed to the recovery of these patients. CT and MRI play a crucial role in both the diagnosis and correct puncture and incision for drainage of the deep neck space infection. © The Foundation Acta Radiologica 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.