The aim of this study is to compare the efficiency of radiopaque dye, decalcification, and histological sectioning in detection of accessory canals in mandibular 1st molars. 30 Extracted mandibular 1st molars were selected. The teeth selected for the study were stored in normal saline. Endodontic access openings were made using a round bur and pulp tissue was removed from the pulp chamber using a standard spoon excavator. Root canal contents were extirpated using barbed broach. Complete debridement of root canals was done using files No. 8 to 25, with copious irrigation using 3% sodium hypochlorite. The teeth were placed in separate bottles containing normal saline and were labeled. Three different methods were used to study the accessory canals, viz, Radiopaque dye, decalcification, and histologic sectioning. According to this study, The incidence of lateral and accessory canals for the mandibular first molar is 46.6%. Results showed that Histological sectioning was significantly ( P = 0.048) better than dye method , but the difference between the Histological sectioning and decalcification was not significant.