INTRODUCTION: The most important aims of root canal preparation are the removal of vital pulp tissue, remaining necrotic debris and infected dentin, eliminating the bulk of bacteria present in the root canal system. The aim of this study was to compare the cleaning efficacy of hand K-Flexofiles and rotary RaCe and K3 instruments in root canal preparation. MATERIALS AND METHODS: A total of 60 single rooted teeth with maximum curvature of <20º were selected and divided into three groups of 20 teeth each. Canals were prepared with K-Flexofiles, K3 and RaCe instruments using crown down preparation technique, up to size #30. After instrumentation, the root canals were flushed with 5 mL of 2.5 % NaOCl solution. The amount of debris and smear layer was quantified on the basis of Hulsmann method using a scanning electron microscope. The data were statistically analyzed with one-way ANOVA test at a significance level of P<0.05. RESULTS: None of the three groups achieved completely debrided root canals.. In general, K-Flexofiles were able to achieve cleaner canals compared to K3 and RaCe instruments (P<0.05). There were no significant differences between three groups in smear layer removal throughout the root canal walls (P<0.05). CONCLUSION: K-Flexofiles group had less remained debris when compared to K3 and RaCe instruments.