Purpose: The incidence of deep cervical space infections has decreased after the introduction of antibiotics and improvement of oral hygiene, but they still may be lethal especially when life-threatening complications occur. In this article, we try to find out whether there are predisposing factors related to complicated deep cervical space infections and prolonged hospitalization. Materials and Methods: We conducted a retrospective analysis of medical records of 196 patients with deep neck infections during the period from March 1996 to February 2002. Among the 196 patients, 15 patients developed lethal complications. As for data analysis, multiple regression and logistic regression with dummy variable were used. Results: In multiple regressions, patients with older age or with neck swelling, trismus, underlying diseases, complications, and C-reactive protein more than 100 μg/mL stayed longer in the hospital, and the P value reached statistical significance (P <.05). In logistic regression, male patients and patients with neck pain had negative correlation, and the P value reached statistical significance (P <.05). Patients with neck swelling and patients with respiratory difficulty had positive correlation, and the P value reached statistical significance (P <.05). That means female patients, patients with neck swelling, and patients with respiratory difficulty were more likely to have complicated deep neck infections. Conclusion: Complicated deep neck infections remain potentially fatal, but the morbidity and mortality can be reduced. Doctors should pay more attention to those high-risk patients; they are female patients, patients with neck swelling, and patients with respiratory difficulty. (This is a US government work. There are no restrictions on its use.)