Background: Endodontic therapy or root canal therapy is a treatment sequence for the infected pulp of a tooth which results in the elimination of infection and the protection of the decontaminated tooth from future microbial invasion. The present study was conducted to assess the causes of endodontic failures. Materials & Methods: The present study was conducted on 100 patients of both genders. A total 220 endodontic treated teeth were evaluated. Intraoral periapical (IOPA) radiograph was used for assessment of presence or absence of periapical radiolucency, quality of obturation, missed canal, dislodged/fractured restorations, iatrogenic problems: perforation, file separation, ledges etc. Results: Out of 100 patients, males were 60 and females were 40. The difference was non- significant (P-0.5). Common cause of failure was missed canal (maxilla- 40%, mandible- 45%), inadequate obturation (maxilla- 45%, mandible- 50%) and fractured coronal obturation (maxilla- 15%, mandible- 5%). The difference was significant (P<0.05). Conclusion: Endodontic failure is not uncommon phenomenon. Common causes are missed canal, inadequate obturation and fractured coronal obturation. Periodic evaluations of cases are required to prevent developing complications. Key words: Dislodged, Endodontic, Obturation