Apical seal in blood or dry root canal is a problem in endodontic treatment. Failure of apical seal causes inflammatory reaction and failure root canal treatment. Because of the sealer properties, root canal should be dry for obturation. But hydrophilic sealers can adhere to root canal walls nowadays and this problem is still controversial. This study aimed at determining the apical microleakage of AH26 and MTA Fillapex sealers in dry and bloody condition. Methods: This experimental in vitro

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... dy was done on 48 extracted central teeth. The researchers used the Mtwo rotary files for root canal instrumentation. In this process, the teeth were divided into four groups (2 dry groups and 2 bloody groups) and two groups as positive and negative control (each group of 4 teeth). All sealers were prepared according to the factory instruction and the obturation was done with gutta-percha and sealer. After 7 days in 100% moisture condition, the teeth were placed in the ink for 3 days and then were cut across longitudinal axis and the level of microleakage was measured by stereomicroscope. Finally, the data were analyzed by SPSS software, ANOVA, Chi-Square and t-test statistical tests. Results: The mean of MTA Fillapex and AH26 apical microleakage in blood groups were (448.61±34.67) Mm and (429.84±31.63) Mm respectively. The minimum microleakage belonged to AH26 sealer, but it was not significant. Conclusion: AH26 sealer is a better barrier against microleakage in comparison with MTA Fillapx, although it is not significant. Also, the evidence suggests drying the canal leads to a better apical seal and the blood significantly increases apical microleakage.