This study reviews our experience with deep neck infections and tries to identify the predisposing factors of life-threatening complications. A retrospective review was conducted of patients who were diagnosed as having deep neck infections in the Department of Otolaryngology at National Taiwan University Hospital from 1997 to 2002. Their demographics etiology, associated systemic diseases, bacteriology, radiology, treatment, duration of hospitalization, complications, and outcomes were reviewed. The attributing factors to deep neck infections, such as the age and systemic diseases of patients, were also analyzed. One hundred eighty-five charts were recorded; 109 (58.9%) were men, and 76 (41.1%) were women, with a mean age of 49.5 +/- 20.5 years. Ninety-seven (52.4%) of the patients were older than 50 years old. There were 63 patients (34.1%) who had associated systemic diseases, with 88.9% (56/63) of those having diabetes mellitus (DM). The parapharyngeal space (38.4%) was the most commonly involved space. Odontogenic infections and upper airway infections were the two most common causes of deep neck infections (53.2% and 30.5% of the known causes). Streptococcus viridans and Klebsiella pneumoniae were the most common organisms (33.9%, 33.9%) identified through pus cultures. K. pneumoniae was also the most common infective organism (56.1%) in patients with DM. Of the abscess group (142 patients), 103 patients (72.5%) underwent surgical drainages. Thirty patients (16.2%) had major complications during admission, and among them, 18 patients received tracheostomies. Those patients with underlying systemic diseases or complications or who received tracheostomy tended to have a longer hospital stay and were older. There were three deaths (mortality rate, 1.6%). All had an underlying systemic disease and were older than 72 years of age. When dealing with deep neck infections in a high-risk group (older patients with DM or other underlying systemic diseases) in the clinic, more attention should be paid to the prevention of complications and even the possibility of death. Early surgical drainage remains the main method of treating deep neck abscesses. Therapeutic needle aspiration and conservative medical treatment are effective in selective cases such as those with minimal abscess formation. (c) 2004 Wiley Periodicals, Inc.