Background and Aim: Traditional methods for establishing working length include the use of radiography which is technique sensitive in both their exposure and interpretation. Electronic apex locators are well known for accurate determination of working length. This study was aimed to compare the working length using two different electronic apex locaters and to compare the electronic apex locator method with radiographic method. Materials & Methods: Authors studied fifty single rooted teeth of patients of ages 15-30 years. The root canals were further instrumented to size 20 K file. Two apex locators Root ZX II and ProPex II with identical frequencies were used. The position of the major foramen in relation to the anatomic apex and the presence of apical resorption were evaluated for each tooth by surgical microscope at 15X. Measurement was read to the nearest 0.5mm and the actual working length was established by subtracting 0.5mm from the true canal length. The distances measured between the two Electronic Apex Locator groups were compared. Statistical Analysis and Results: Data was sent for statistical analysis using statistical software Statistical Package for the Social Sciences. 50 measurements for each Electronic Apex Locators were obtained. The mean distance between the file tip and the minor diameter was +0.0060 mm (±0.49 mm) for the Root ZX II. The mean distance was +0.0170 mm (± 0.55 mm) for the ProPex II. The Paired sample t-test showed that there was no statistical significant difference between the results of Root ZX II and ProPex II. Conclusion: The use of Electronic Apex Locators is a reliable method for determining root canal length. The Root ZX II was more efficient in locating the minor diameter (±0.5 mm) (76% accuracy) than the Propex II (66%). Root ZX II with the auto-stop function had more accurate readings than the Propex II.