Background: Tooth impaction is a common occurrence and surgical removal of impacted teeth is the commonest of routine dental surgical procedures. Various pathological conditions like cysts, tumors, abscess etc. have been associated with partially or completely unerupted tooth. Aim: To determine the histopathological incidence of cysts and tumours associated with impacted mandibular third molar. Methods: A retrospective study was conducted on 85 formalin-fixed, paraffin-embedded tissue blocks, including 85 cases of impacted mandibular third molars associated with pathologies which are histopathologically diagnosed using H & E staining. After data collection, statistical analysis was done. Results: In our study, dentigerous cyst have the highest incidence (22.35%) followed by ameloblastoma (14.11%), odontogenic keratocyst (9.4%) and calcifying cystic odontogenic tumour (2.35%). Conclusion: Follicular tissue was obtained from extraction of impacted teeth should be sent for a histopathologic investigation and attention should be focused on age, gender, site and type of impaction for the treatment planning of an impacted third molar.