The proper knowledge of both the external and internal anatomy of teeth is mandatory for adequate root canal treatment. Permanent mandibular premolars are usually single rooted with single root canal. Variations of having more than one canal/root also exist.The Incidence of three canals in mandibular second premolar has been reported to be 0.46–0.5%. The present case describes root canal treatment of mandibular second premolar with two roots & three canals confirmed with CBCT evaluation. The clinicians must be aware of such anatomical variations and be able to use variety of tools for adequate diagnosis and management