Purpose: present study designed to evaluate the influence of coronal preflaring on the amount of debris extruded apically during preparation of the root canal using reciprocating systems,Reciproc and WaveOne Gold.Materials and Methods:Sixty mandibular first molars with canal curvature between 25°-35° used and divided into 2 groups(Ι and ΙΙ) according to the method of preparation of the root (30 samples each); Group I: were prepared with coronal preflaring , Group II: were prepared without coronal preflaring. The groups further subdivided into 2 subgroups (A, B) according to the reciprocating file system used (15 samples each); Subgroup A: instrumented using Reciproc , Subgroup B: instrumented by WaveOne Gold .samples mounted in a model used to measure the amount of debris extruded apically.Results: In Reciproc subgroup, no statistical difference in samples prepared with and without coronal preflaring in the median of debris extruded apically (P>0.05). WaveOne Gold subgroup, samples prepared with coronal preflaring showed lower value of apically extruded debris than samples prepared without coronal preflaring. However,there was no statistical difference between the samples in the median of debris extruded apically (P > 0.05).In group I and II: (with and without coronal preflaring respectively), no statistically significant difference between Reciproc and WaveOne Gold in the median of debris extruded apically (P> 0.05). Conclusions:Reciproc and WaveOne Gold presented similar behavior regarding the amount of debris extruded apically during preparation .Coronal preflaring has no effect on the amount of debris extruded apically during preparation using reciprocating single-file systems,Reciproc and Wave One Gold.