Objectives: To compare the efficiency of two engine driven rotary systems (theSafeSider and the Protaper universal retreatment files) with a manual technique (Hfiles)in removal of gutta-percha from curved root canal. A total of 60 extractedmandibular human molars with fully formed apices and with curvature less than 25degree were selected. The root canals were prepared, then obturated gutta-perchaand AH Plus sealer. The root canals were divided into 6 groups of 10 root canalseach according to retreatment technique as the following: group(A1) Hfile+solvent, group(A2) H-file, group(B1) Protaper universal retreatment2files+solvent, group(B2) Protaper universal retreatment files, group(C1) SafeSiderreamers+solvent, group(C2) SafeSider reamers. Five types of data were recordedfor all the specimens: time for reaching the original working length, total time forretreatment, canal wall cleanliness, apically extruded debris and procedural errors.Results: with no solvent the SafeSider showed the statistically significant highestmean total retreatment time , H-file showed the highest incidence of apicallyextruded debris with and without the presence of the solvent, the SafeSider showedthe lowest gutta-percha% in the coronal and middle segments with solvent whileH-file +solvent showed the statistically significant lowest mean sealer%.Conclusion: None of the retreatment techniques produced complete removal ofthe filling materials from the root canals. The use of H-file with the solventreduced the remnants of AH Plus sealer in the apical middle and coronal third