The purpose of this study was to compare the apical microleakage in root canal filled with Resilon by several self-etching primers and methacrylate-based root canal sealer. Seventy single-rooted human teeth were used in this study. The canals were instrumented by a crown-down manner with Gate-Glidden drills and .04 Taper Profile to ISO #40. The teeth were randomly divided into four experimental groups of 15 teeth each according to root canal filling material and self-etching primers and two control groups (positive and negative) of 5 teeth each as follows: group 1 -gutta percha and AH26 � sealer; group 2 -Resilon, RealSeal ™ primer and RealSeal ™ sealer; group 3 -Resilon, Clearfil SE Bond � primer and RealSeal ™ sealer group 4 -Resilon, AdheSe � primer and RealSeal ™ sealer. Apical leakage was measured by a maximum length of linear dye penetration of roots sectioned longitudinally by diamond disk. Statistical analysis was performed using the One-way ANOVA followed by Scheffe' s test. There were no statistical differences in the mean apical dye penetration among the groups 2, 3 and 4 of self-etching primers. And group 1, 2 and 3 had also no statistical difference in apical dye penetration. But, there was statistical difference between group 1 and 4 (p < 0.05). The group 1 showed the least dye penetration. According to the results of this study, Resilon with selfetching primer was not sealed root canal better than gutta precha with AH26 � at sealing root canals. And there was no significant difference in apical leakage among the three self-etching primers. [J Kor Acad Cons Dent 33(2):133-140, 2008]