The purpose of this study was to quantify the amount of remaining gutta-percha/sealer on the walls of root canals when three types of nickel-titanium rotary instruments (Profile, ProTaper and K 3 ) and a hand instrument(Hedstrom file) used to remove these materials.The results of this study were as follows: 1. In the total time for gutta-percha removal, Profile group was the fastest and followed by K 3 , Protaper, Hedstrom file group. 2. In case of the evaluation of the volume of remained gutta-percha from radiograph, K 3 group got the highest score and followed by Protaper, Hedstrom file, Profile group in the apical 1/3. 3. In case of the evaluation of the volume of gutta-percha remained from stereomicroscope, K 3 group got the highest score and followed by Protaper, Hedstrom file, Profile group in the apical 1/3. These results showed that instrumentation using nickel-titanium rotary instrument groups was faster than that using hand instrument group. The effect of gutta-percha removal using Profile group was better than that using Protaper and K 3 group in the nickel-titanium rotary instrument groups. [J Kor Acad Cons Dent 29(3):212-218, 2004]