of three rotary Ni-Ti retreatment systems in root canal retreatment. Remaining obturating material on canal walls, time required for retreatment process, number of fractured files, amount of debris extrusion was evaluated. The total number of sample was 60 canals in 30 mesial root of lower mandibular first molar type III and was randomly divided into 3 groups of 20 canals according to retreatment system used. In Group (I), Group (II), Group (III) retreatment was done using Protaper universal retreatment files Fanta AF retreatment files and M3 Pro gold retreatment files respectively. Fanta and M3 progold retreatment file systems has higher efficiency in removal of obturating material than Protaper retreatment file system with statistically significant difference. Protaper retreatment file system was faster than Fanta and M3 progold retreatment file with significant difference. 3 protaper, 2 Fanta, 5 M3 progold files were broken. Fanta showed the highest amount of debris extrusion with significant difference. Under the circumstances of this study, it can be concluded that fanta and M3 progold file has higher efficiency in removal of obturating material, protaper faster in retreatment, different root section affects amount of remaining root filling material, M3 progold file system has more broken files, fanta extrude more debris than protaper and M3 progold.