The aim was to assess the presence of smear layer after canal instrumentation with two reciprocating rotary systems and a continuous motion one. Thirty canals were shaped with Reciproc, WaveOne or Mtwo systems. Smear layer was assessed following a three value scale at coronal, middle and apical levels with a scanning electron microscopy. Reciproc scores: coronal third, 20% of the cases: 0, 60%: 1, 20%: 2; middle third, 10%: 0, 20%: 1, 70%:2; apical third: 2 in all cases. WaveOne scores: coronal third, 0 (40%), 1 (30%) and 2 (30%); middle third, 0 (20%), 1 (50%), 2 (30%); apical third, 0 (20%), 2 (80%) of cases. MTwo scores: coronal third 0 (50%), 1 (30%) 2 (20%); middle third 0 (20%), 1 (50%), 2 (30%); apical third, 0 (10%), 1 (10%), 2 (80%). No significant differences (p>0.05) were found between the three used systems. Key words:Endodontics, reciprocating motion files, rotary file, SEM, smear layer.