Introduction: Coronal anatomic variations in permanent maxillary molars are unusual; conversely variations involving the number of root canals or number of roots are more common. Methods and Materials: This case report presents a successful nonsurgical endodontic therapy of left maxillary first molar with three roots and seven root canals. This unusual morphology was diagnosed using a dental operating microscope (DOM) and confirmed with the help of cone-beam computed tomography (CBCT) images. Results: CBCT axial images showed that both of the palatal and distobuccal roots had Vertucci type II canal pattern, whereas the mesiobuccal root canal showed a Sert and Bayirli’s type XV configuration. Conclusion: The use of a DOM and CBCT imaging in endodontically challenging cases can facilitate a better understanding of the complex root canal anatomy, which ultimately enables the clinician to explore the root canal system, and therefore treat it far more efficiently.