Introduction: This study evaluated the amount of apically extruded debris in the retreatment of curved root canals using different nickel-titanium (NiTi) systems: the ProTaper Universal Retreatment (Dentsply Maillefer, Ballaigues, Switzerland), Mtwo Retreatment (VDW, Munich, Germany), D-Race Retreatment (FKG Dentaire, La Chaux-de-Fonds, Switzerland), R-Endo Re treatment (Micro-Mega, Besancon, France), and Reciproc (VDW) systems. Methods: One hundred human mandibular premolars with curved root canals were prepared with the Reciproc #25. 08 NiTi system filled with AN Plus Jet (Dentsply DeTrey, Konstanz, Germany) sealer and gutta-percha and divided into 5 groups (n = 20). The canal filling was removed with the Pro Taper, Mtwo, D-Race, and R-Endo retreatment systems and Reciproc instruments. Final preparation was done with the Reciproc #40.06 NiTi system. Extruded debris was collected in preweighed Eppendorf tubes. The times required for retreatment were recorded. Results: Reciproc produced significantly (P <.001) more debris than the other systems. ProTaper R and Mtwo R produced significantly (P <.001) more debris than D-Race and R-Endo. The Reciproc group required significantly (P <.001) less preparation time than the other groups. Conclusions: In the retreatment of curved root canals, the Reciproc system extruded significantly more debris than the rotary retreatment NiTi systems. In addition, the ProTaper and Mtwo retreatment systems extruded significantly more debris than the R Endo and D -Race systems. The Reciproc system was significantly faster than the rotary retreatment systems.