The purpose of this study was to determine  the amount of remaining Ca(OH)2 after three removal techniques as well as determining its influence on apical seal. 80 extracted mandibular premolars were prepared with  ProTaper system®, dressed with Ca(OH)2 paste and stored 10% humidity at 37º C for 7 days. Experimental groups according to the removal technique were : NaCIO 2.5% +  EDTA (G1), NaCIO 2.5% + EDTA 18% and ultrasonic activation (G2); NaCIO and ultrasonic activation (G3). 40 teeth were longitudinally split in order to measure remaining Ca(OH)2. The other 40 specimens were obturated  with ultrasonic condensation of gutta-percha technique. These teeth were cleared and apical leakage was measured. Statistical analysis showed  difference among groups with respect to Ca(OH)2 removal  (P<0.03), Group G2 showed least amount of remaining Ca(OH)2. Likewise, leakage results showed statistical difference among groups (P<0.01). Group 2 showed best results with respect to leakage. There was no statistical difference  between groups 1 and 3.Conclusion: Irrigation with NaCIO 2.5% EDTA 18% and ultrasonic activation proved to be most effective in removing Ca(OH)2 from canal walls. Calcium hydroxide  medication residuals inside canals might increase apical leakage.