Endodontic treatment success is obtained by thorough chemomechanical preparation and three dimensional obturation of the root canal system. Maxillary first premolar most commonly presents with two roots with two canals. The most common variation in maxillary first premolar is the presence of three canals and can be frequently missed leading to endodontic treatment failure. This case report describes two cases of endodontic management of maxillary first premolars with three canals. Additional canal was identified through exploration and multiple radiographs with mesial and distal eccentric shifts. Appropriate knowledge regarding the possible anatomic variations and good clinical skills are essential prerequisites for a successful endodontic treatment outcome. Missed canal and inadequate cleaning and shaping contributes to persistent pain, sensitivity leading to treatment failure.