Numerous case reports emphasise the importance of thorough knowledge of the anatomic morphology in the maxillary molars for the success of root canal treatment. The aim of this paper was to present a case of a maxillary second molar with four roots (two palatal roots) and four distinct canals requiring root canal therapy. Root canal treatment was performed using nickel-titanium rotary files. In addition, the role of cone beam computed tomography as an objective tool for confirmatory diagnosis and successful treatment is demonstrated. Properly prepared access cavity and cone beam computed tomography (CBCT) scanning revealed unusual root morphology and led to a favourable outcome for root canal treatment. A thorough knowledge of possible variations in internal anatomy of human teeth is important for successful root canal treatment. Schlagwörter: anatomical variations, cone beam computed tomography, maxillary molars, root anatomy