Successful root canal treatment depends on adequate cleaning, shaping and filling of the root canal system. Mandibular molars demonstrate considerable variations with respect to number of roots and root canals. The presence of middle mesial (MM) root canal of mandibular  molars has been reported by various authors. This paper discusses the endodontic management of the rare anatomical complexity middle mesial canal in mandibular first and second molar and also serves to remind the clinicians that such anatomical variations should be taken into account during the endodontic treatment of the mandibular molars.