Introduction: This study compared the effect of immediate versus delayed post space preparation on the apical seal using three different sealers. Materials and Methods: Seventy single rooted teeth were biomechanically prepared and obturated with gutta‑percha and 3 sealers: AH Plus, MTA and BioRoot RCS sealer. Teeth were divided randomly into eight groups, post spaces were prepared using Gates Glidden drills and peso reamers immediately for group I, III and V. For groups II, IV and VI prepared after storage of the specimens in 100% humidity for one week. Groups VII and VIII were control groups. The samples were kept in methylene blue dye, centrifuged at 3000 rpm for 3 min sectioned and then measured under stereomicroscope for apical leakage. Results: The results of this study showed that apical microleakage was observed in all the groups. Conclusion: Less leakage is seen when post space is prepared immediately.