Materials & Methods: Seventy two freshly extracted single root canal human premolars were selected for this study. The canals were instrumented with hand files using step back technique. Six specimens were assigned for positive control and six for negative control groups. The rest of the specimens were randomly divided into three groups of 20 and obturated with gutta percha and one of the aforementioned sealers. Microleakage in all groups was assessed, 2 weeks and 3 months after obturation of canals, by means of fluid filtration. The data were analyzed using repeated measurement and post-hoc Tukey test. The level of significance was set at P<0.05.

 Result: In none of the assessment intervals, there was a significant difference between AH-plus and MTA Fillapex. iRoot SP had less microleakage compared to other groups significantly (P<0.001). Microleakage assessments revealed no significant differences between 2 weeks and three months in all groups. 

 Conclusion: iRoot SP sealer had significantly less microleakage compared to MTA Fillapex and AH-Plus.