Introduction: infections of the head and neck spaces are serious and dangerous due to vicinity to the great vessels and mediastinum. The most common source of infection leading to head and neck space abscess, are dental infection. This retrospective study was performed to determine the prevalence of head and neck space infections following dental infections, the spaces involved, the most common microorganisms involved in these infections and to determine the prevalence of head and neck space infections according to age and sex of the patients.
Materials and Methods: In this retrospective study, the charts of 241 patients with head and neck space infections referring to Khalili hospital during the past 10 years was reviewed and data well assessed.
Results: The most common source of head and neck space infections was dental infections occurring in 141 patients (58.5%). From these 141 patients, 79 patients were male and 62 patients were female. The most common age of involvement was the 3^rd decade (39 patient 27 6%). The second most common cause was tonsillitis occurring in 33 patients (13.7%). The most common spaces involved in 141 patients with head and neck space infection following dental infections, were: simultaneous involvement of submandibular, sub mental and sublingual space bilaterally (Ludwig's angina) in 53 patients (37.6%) followed by sumbandibular space in 45 patients (31.9%) and Para pharyngeal space in 37 patients (26.2%).  Culture has been performed in only 34 patients from which bacterial growth occurred in 18 cases. The most common organism was non hemolytic streptococci (11 cases).
Conclusion: Head and neck space infection are dangerous and life threatening conditions that occur most commonly following dental infections so it seems that escalating the general knowledge about oral health, increasing dentistry centers and early and proper management of dental infections have a major role in reducing the incidence of head and neck abscesses.