The aim of this study was to compare the effects of different NaOCl and EDTA formulations with/without ultrasonic use on smear layer removal and root canal surface characteristics after post space preparation. Study design: After post space preparations, forty-six teeth were subjected to different post space irrigation regimes; G1, 17% EDTA; G2, 17% EDTA+Ultrasonic activation; G3, EDTA-T; G4, EDTA-T+Ultrasonic activation; G5, NaOCl; G6, NaOCl+Ultrasonic activation. Specimens were examined under scanning electron microscope and scored for debris and smear layer removal and dentinal tubule opening and statistically analyzed with Kruskal Wallis and Dunn's test. Significance value was set at p<0.05. Results: EDTA and EDTA-T groups showed significantly better efficiency than the other groups in the each parts of the samples in terms of smear layer removal (p<0.05). In terms of dentinal tubule opening, EDTA, EDTA+Ultrasonic and EDTA-T groups had significantly better efficacy than the other groups in the middle and coronal parts of the samples (p<0.05). Conclusions: Ultrasonic activation did not significantly improve the efficiency of the irrigants.