This study sought to compare the root canal debridement ability of Neolix, Reciproc and ProTaper rotary systems in long oval-shaped root canals. Eighty five extracted single-rooted human teeth with long oval-shaped single root canals were selected and divided into three experimental groups(n=25) and one control group (n= 10). Root canals were filled with Vitapex radiopaque contrast medium and prepared with Neolix, Reciproc or ProTaper systems. The control group only received irrigation. Digital radiographs were obtained at baseline and postoperatively and subjected to digital subtraction. The percentage of reduction in contrast medium was quantified at 0-5 mm and 5-10 mm distances from the apex. The data were analyzed using one-way ANOVA and t-test. The mean percentage of the contrast medium removed was not significantly different in the 0-5mm segment among the three groups (P=0.6). In the 5-10mm segment a significant difference was found in this regard among the ProTaper and Reciproc groups (P=0.02) and the highest mean percentage of contrast medium was removed by ProTaper. But, difference between ProTaper and Neolix as well as Neolix and Reciproc was not significant. In Neolix (P=0.024) and Reciproc (P=0.002) systems, the mean percentage of the contrast medium removed from the 0-5mm segment was significantly greater than that in 5-10mm segment; however, this difference was not significant in ProTaper group (P=0.069). Neolix single-file system may be a suitable alternative to ProTaper multiple-file system in debridement of long oval shaped canals.