Aim: The objective of this study was to evaluate in vitro the accuracy of two electronic apex locators (Root ZX, J. Morita, Kyoto, Japan; and Apex Pointer™, Micro-Mega®, Besançon, France) for determining the root canal lengths of primary teeth with or without root resorption. Materials and Methods: Twenty primary human teeth, with or without root resorption, were used. After accessing the canals, 53 root canals were measured by the direct method and by two electronic apex locators (EALs). The actual length (AL) of each root canal was subtracted from the electronic measurement (EM) obtained by each device. The mean value of differences was obtained and percentages of acceptable measurements were determined. Statistical analysis was performed using ANOVA and the unpaired Student's t-test. Results: The mean values of differences between AL and EM for the Root ZX device were -0.07 mm (± 0.43) and 0.1 mm (± 0.63) in teeth without and with resorption, respectively. Corresponding values obtained by the Apex Pointer™ device were 0.01mm (± 0.47) and 0.09mm (± 0.63), respectively. The results showed that the majority of EMs were within ± 0.5 mm of the ALs. It was found that the accuracy of Root ZX was 75% and 76% for roots without and with resorption, respectively, while the Apex Pointer™ showed accuracies of 68% and 60%, respectively. No statistically significant difference was found between canal lengths obtained by both EALs and directly determined root canal lengths (P > 0.05). For the two devices, no significant differences were found between roots without and with resorption (P > 0.05). Conclusion: The two electronic apex locators (Root ZX and Apex Pointer™) showed accuracy in determining root canal length in primary teeth with and without root resorption. Keywords: electronic apex locator, endodontic treatment, primary teeth, root canal length