Statement of problem: Studies have shown the effect of sealers used with master cones in order to gain better apical multi dimensional sealing. This goal is considered to be effective in treatment prognosis and blocking micro-organisms and limiting their activities. Applicable sealers should have advantages such as little dissolution and proper adaptation to periapical tissue. Calcium phosphate and hydroxy apatite are compounds that have shown significant effect in recovery of osseous lesions.Purpose: The aim of this study was to apply a mixture of these materials as sealer, named Apatite Root Sealer, with gutta percha in root canals and compare its micro leakage with AH26 sealer.Materials and method: In this experimental study 26 extracted single-root human adult teeth, with same size and without curve were selected. The apical third of roots were prepared by step-back technique and Race rotary files (6%) up to MAF# 40 and the coronal two thirds were prepared by gates gliddens. The canals were irrigated with sodium hypochlorite 5.25%. The teeth were divided in two test groups of 10 and two control groups of three teeth. Group A: Canals were filled with gutta percha & Apatite Root Sealer. Group B: Canals were filled with gutta percha & AH26 sealer. The access cavities were sealed with Glass ionomer and then samples were placed in incubator at 37ه C and 100% humidity for about 48 hours. After sealing the roots with two layers of nail polish and sticky wax except for the two mm of apical area, the teeth were placed in silver nitrate 50% for six hours and then rinsed and exposed to florescent light before floating in developing solution for about two hours. Specimens were sectioned longitudinally from buccal to lingual and examined under a stereomicroscope by 0.1 mm accuracy. The dye penetration level was measured and analyzed using T-student statistical test.Results: Measuring the samples showed that dye penetration in Apatite root sealer group was more than AH26 group, which was significantly comparative (p<0.001).Conclusion: Since the resin-based sealer (AH26) was more trustworthy and effective in achieving apical seal in comparison to the Apatite root sealer, its application is more recommended.Key words: Apical leakage- Apatite root sealers- AH26 sealer