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Background and Objective: Impacted molars teeth, especially third molar, are important in most branches of medical sciences. The angular position of molar teeth is in side effects and therapeutic regiment. This study was conducted to determine the angle of the impacted mandibular third molars. Materials and Methods: This descriptive study was carried out on 429 patients (269 men and 160 women) selected for surgery on impacted mandibular third molar in the oral and maxillofacial surgery clinic in Gorgan, Iran during 2010-11. Pre-operative diagnosis was done by physical examination and OPG radiography. Demographic characterstics including age, gender, ethnicity, impaction angle were recorded for each subject. Data were analyzed using SPSS-16, independent t-test and chi-square test. Results: Totally, 480 impacted third molars were studied. Mean age of patients was 26.06±6.21 years. Impaction of the third molar was more prevalent among men (62.7%) than women (38.30%). Impacted mandibular third molar of 189 people (44.1%) were in left side in 200 people (46.6%) were in right side and in 40 people (9.3%) were bilateral. According to impaction angle, mesioangular (41.7%) and distoangular (3.5%) types had the highest and the lowest frequency, respectively. In bilateral cases, the mesioangular-mesioangular type (48.8%) was the most prevalent. The mesioangular type was the most prevalent in all ethnic groups. The most prevalent angular position of the impacted third molar was the mesioangular type in both sexes. Conclusion: This study showed that the most prevalent angular position of impacted mandibular third molar is the mesioangular type.