Lack of proper sealing of canal leads leakage, and penetration of microorganisms into the canal which is the most important factor for failure of root canal treatment. Different methods have been used to determine the apical seal. Objectives: The purpose of this study was to compare the apical leakage using dye penetration and electrochemical methods each successively used on the same teeth. Methods: 22 freshly extracted anterior single root human teeth with straight canals were selected. The specimens were divided randomly into three groups. Group 1 consisted of 16 teeth that served as case group, group 2 consisted of 4 teeth that served as positive group, and group 3 consisted of 2 teeth that served as negative group. Root canal of the case group and negative group were filled with standardized lateral condensed gutta–percha and ZOE sealer, and positive group with gutta–percha and no sealer. The external surface of each tooth were coated with two layers of the nail polisher, except for the apical 2mm and coronal portion. Leakage of each tooth was measured by using electrochemical test. Two copper wires were used as electrodes and normal saline solution was used as electrolyte. Then coronal portion of root, with use of ZOE cement were obturated and coated with two layers of the nail polisher.The teeth immersed in 2% methylen blue dye for 12 hours and were washed in tap water for 3 minutes. The roots were then split longitudinally and dye leakage was assessed for each tooth. Results: No correlation was found among the results obtained with the two methods. Conclusions: This study shows that several studies are necessary before evaluation of the marginal leakage.