OBJECTIVE The root anatomy and position of mandibular third molars are important factors in assessing the level of difficulty of surgical removal procedures. In this light, this study aims to identify the most frequent position and the root anatomy of mandibular third molars. METHODS The study sample comprised 1205 mandibular third molars from 710 panoramic radiographs evaluated. Regarding the position, all of them were based on Pell and Gregory's and Winter's classifications. The root anatomy was classified according to the type and number of roots, as well as the presence of laceration, fusion, or divergence. Gender and the quadrant were also considered. Following an interexaminer analysis, a statistical analysis was performed using the Kappa test. RESULTS The results showed that the IA (40.3%) and mesioangular (53.8%) position was predominant in mandibular third molars. Regarding the anatomy, the most common were two roots (98.3%), of the conical simple type (88.9%), with absence of laceration (89.2%), divergence (84%), and fusion (80%). CONCLUSIONS The present study showed that the most prevalent mandibular third molar type in Brazilian patients was the IA and mesioangular position, with simple root anatomy. The result of this study can assist oral surgeons to better plan and assess the level of difficulty of surgical removal procedures.