Introduction: The purpose of this study was to evaluate the weight of debris extruded apically from teeth using different in vitro preparation techniques. Methods: Sixty-eight extracted human mandibular premolars with single canals and similar lengths were instrumented using ProTaper F2 (25,.08; Dentsply Maillefer, Ballaigues, Switzerland), the Self-Adjusting File (1.5-mm diameter; Re-Dent Nova, Ra'anana, Israel), Revo-S SU (25,.06; MicroMega, Besancon, France), or Reciproc (R25; VDW GmbH, Munich Germany). Debris extruded during instrumentation were collected into preweighed Eppendorf tubes. The Eppendorf tubes were then stored in an incubator at 70 degrees C for 5 days. The Eppendorf tubes were weighed to obtain the final weight of the Eppendorf tubes when the extruded debris were included. Three consecutive weights were. obtained for each tube. Results: There were no statistically significant differences among the groups (P=.218). The ProTaper group produced the highest mean extrusion value. The Reciproc produced less debris compared with all the other instruments (P >.05). Conclusions: All instrumentation techniques were associated with extruded debris.