Aim: To report the root canal treatment performed on a three-rooted maxillary first premolar. Summary: Many of the difficulties found in endodontic therapy are caused by variations in root canal anatomy. Most commonly bi-rooted, the maxillary first premolar can also have three roots with three independent canals at the apex. This case report describes the root canal treatment performed on a maxillary first premolar with three independent root canals in three distinct roots. Good knowledge of the endodontic anatomy and good interpretation of the periapical radiographs are very important skills in recognising the unusual morphology of the teeth and performing a predictable endodontic treatment. Special care needs to be taken during clinical examination, refining the access cavity, locating the orifices of the root canals on the pulpal floor and cleaning, shaping and filling all identified root canals. Keywords: endodontic therapy, maxillary first premolar, root canal anatomy