Aim: The present study compared the accuracy of Root ZX mini and CanalPro in determination of working length in open apex, location of lateral canals at different levels and determination of extent of perforating internal root resorption. Methods: Seventy-five decoronated single rooted teeth with single canal were divided into three groups- simulated lateral canals at 3, 5 and 8 mm from the apex, simulated perforating internal root resorption and simulated open apex. Actual length was measured by visual method and electronic length of samples embedded in alginate model. Results: The accuracy of both the apex locators in EL determination was significantly higher in apical lateral canals compared to middle and coronal canals and in apical extent of internal resorption as compared to coronal extent (P<0.05). Conclusion: Both EAL’s are accurate in working length determination in simulated clinical scenarios.